Method and device for improved communication performance in wireless communication system

ABSTRACT

Disclosed are: a communication technique for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system; and a system therefor. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail, security, and safety related services, and the like) on the basis of 5G communication technology and IoT-related technology. Disclosed is an operating method of a terminal, comprising the steps of: receiving, from a base station, a radio resource control (RRC) message including information for indicating whether to use uplink data compression (UDC); receiving data from an upper application layer of the terminal; compressing the data and encoding the compressed data; generating an uplink data compression (UDC) header and a service data adaption protocol (SDAP) header together; generating a block to which the UDC header and the SDAP header are bonded in the encoded data; and transmitting the block to a lower layer of the terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of International Application No.PCT/KR2019/000197 filed on Jan. 7, 2019, which claims priority to KoreanPatent Application No. 10-2018-0001821 filed on Jan. 5, 2018 and KoreanPatent Application No. 10-2018-0036079 filed on Mar. 28, 2018, thedisclosures of which are herein incorporated by reference in theirentirety.

BACKGROUND 1. Field

The disclosure relates to a next-generation wireless communicationsystem. The disclosure relates to a terminal and a base station in amobile communication system. In addition, the disclosure relates to adata compression processing header non-encryption method and device in anext-generation mobile communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “Beyond 4G Network” or a“Post LTE System”. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-points (CoMP), reception-end interference cancellationand the like. In the 5G system, hybrid FSK and QAM modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have also been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and thebig data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, machine type communication (MTC), andmachine-to-machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud radioaccess network (RAN) as the above-described big data processingtechnology may also be considered an example of convergence of the 5Gtechnology with the IoT technology.

The technical problem to be achieved in the embodiment of the disclosureis to provide a method and device for providing improved communicationperformance in a next-generation wireless communication system.

In addition, the technical problem to be achieved in the embodiment ofthe disclosure is to provide a method that supports a variety ofimplementation structures on the base station side in a next-generationmobile communication system and is capable of reducing the processingburden on the terminal for supporting a service having a high data rateand a low transmission delay on the terminal side.

Unlike the existing LTE, the next-generation mobile communication systemprovides flow-based quality of service (QoS) and introduces a new QoSlayer (service data adaption protocol (SDAP)), which indicates thechange of the flow mapping rule in the access stratum (AS) and thenon-access stratum (NAS) to the wireless protocols of the terminal andthe base station in the user packet. However, the base station cannotrecognize that a new QoS flow has been transmitted until the firstpacket of the new QoS flow transmitted by the terminal arrives, andthus, if there is a lot of buffered data in the data radio bearer (DRB),the delay in transmission of the first packet may be longer. To thisend, the technical problem to be achieved in the embodiment of thedisclosure is to provide a method for processing by the terminal so thatthe scheduler of the base station can quickly recognize and process thereception of the new QoS flow, and for ensuring in-sequence deliverywhen performing QoS re-mapping in response to a change in a DRB.

SUMMARY

An embodiment of the disclosure may provide an operation method of aterminal, the method including: receiving, from a base station, a radioresource control (RRC) message including information indicating whetherto use uplink data compression (UDC); receiving data from an upperapplication layer of the terminal; compressing the data and encryptingthe compressed data; generating an uplink data compression (UDC) headerand a service data adaptation protocol (SDAP) header together;generating a block to which the UDC header and the SDAP header arebonded in the encrypted data; and transmitting the block to a lowerlayer of the terminal.

In addition, according to an embodiment of the disclosure, there may beprovided a terminal including: a transceiver, and a controllerconfigured to control to receive a radio resource control (RRC) messageincluding information indicating whether to use uplink data compression(UDC) from a base station, receive data from an upper application layerof the terminal, compress the data and encrypt the compressed data,generate an uplink data compression (UDC) header and a service dataadaptation protocol (SDAP) header together, generate a block to whichthe UDC header and the SDAP header are bonded in the encrypted data, andtransmit the block to a lower layer of the terminal.

In addition, according to an embodiment of the disclosure, there may beprovided an operation method of a base station including: transmitting aradio resource control (RRC) message including information indicatingwhether to use uplink data compression (UDC) to a terminal; receivingfirst data from the terminal; obtaining an uplink data compression (UDC)header and a service data adaptation protocol (SDAP) header that arebonded in the first data; decoding and decompressing second data fromwhich the UDC header and the SDAP header are removed; and transmittingthe decompressed second data to an upper layer of the base station.

In addition, according to an embodiment of the disclosure, there may beprovided a base station including: a transceiver, and a controllerconfigured to control to transmit a radio resource control (RRC) messageincluding information indicating whether to use uplink data compression(UDC) to a terminal, receive first data from the terminal, obtain anuplink data compression (UDC) header and a service data adaptationprotocol (SDAP) header, which are bonded in the first data, decode anddecompress second data from which the UDC header and the SDAP header areremoved, and transmit the decompressed second data to an upper layer ofthe base station.

The technical problems to be achieved in the disclosure are not limitedto the technical problems mentioned above, and other technical problemsthat are not mentioned will be clearly understood by those skilled inthe art from the following description.

According to an embodiment of the disclosure, it is possible to providea method and device for providing improved communication performance ina next-generation wireless communication system.

In addition, according to an embodiment of the disclosure, it ispossible to provide a header-processing method for compressing user dataand headers of an SDAP-layer device and a packet data convergenceprotocol (PDCP)-layer device, which makes it easy to realize variousimplementations of a base station and is capable of reducing theprocessing burden on a terminal.

In addition, according to an embodiment of the disclosure, by suggestinga structure in which a flow-based QoS is supported by the wirelessinterface and the first packet can be preferentially transmitted for thenew QoS flow in a next-generation mobile communication system, the QoSchange can be quickly identified. In addition, according to anembodiment of the disclosure, when a QoS flow is transmitted to the newDRB in response to a terminal operation, in-sequence delivery isguaranteed, so that frequent QoS flow update operations, which may occurduring out-of-sequence delivery, can be reduced, thereby reducingcomputational complexity at the receiving end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a view illustrating the structure of a next-generation mobilecommunication system;

FIG. 1B is a view for explaining wireless connection state transition ina next-generation mobile communication system;

FIG. 1C is a view for explaining a phenomenon in which a radio accessstate is inconsistent in an LTE system;

FIG. 1D is a view for explaining a method of dealing with a phenomenonin which a radio access state is inconsistent in an LTE system;

FIG. 1E is a flowchart of a process for dealing with a phenomenon inwhich a wireless connection state is inconsistent according to anembodiment of the disclosure;

FIG. 1F is a flowchart showing the operation of a terminal according toan embodiment of the disclosure;

FIG. 1G is a flowchart showing the operation of a base station accordingto an embodiment of the disclosure;

FIG. 1H is a view illustrating the configuration of a terminal accordingto an embodiment of the disclosure;

FIG. 1I is a view illustrating the configuration of a base stationaccording to an embodiment of the disclosure;

FIG. 2A is a view illustrating the structure of an LTE system accordingto an embodiment of the disclosure;

FIG. 2B is a view illustrating the structure of a wireless protocol ofan LTE system according to an embodiment of the disclosure;

FIG. 2C is a view illustrating the structure of a next-generation mobilecommunication system according to an embodiment of the disclosure;

FIG. 2D is a view illustrating the structure of a wireless protocol of anext-generation mobile communication system according to an embodimentof the disclosure;

FIG. 2E is a view illustrating a procedure for configuring whether abase station performs uplink data compression when a terminalestablishes a connection with a network according to an embodiment ofthe disclosure;

FIG. 2F is a view illustrating a procedure and data configuration forperforming uplink data compression according to an embodiment of thedisclosure;

FIG. 2G is a view illustrating an embodiment of an uplink datacompression method according to an embodiment of the disclosure;

FIG. 2H is a view illustrating a procedure and data configuration forperforming robust header compression (ROHC) according to an embodimentof the disclosure;

FIG. 2I is a view illustrating a procedure for generating an SDAP headerfor data received from an upper layer and encrypting the SDAP header ina PDCP-layer device according to an embodiment of the disclosure;

FIG. 2J is a view of a procedure for generating an SDAP header for datareceived from an upper layer in a PDCP-layer device and not performingencryption on the SDAP header according to an embodiment of thedisclosure;

FIG. 2K is a view showing the gain in the structure of the base-stationimplementation when the unencrypted SDAP header according to theembodiment of the disclosure is applied;

FIG. 2L is a view illustrating processing gains obtained in a basestation and a terminal implementation when an unencrypted SDAP headeraccording to an embodiment of the disclosure is applied;

FIG. 2M is a view illustrating processing gains that can be obtainedfrom a base station and a terminal implementation in which ROHC is setwhen an unencrypted SDAP header is applied according to an embodiment ofthe disclosure;

FIG. 2N is a view for explaining generation of an SDCP header for datareceived from an upper layer and application a user data compressionprocedure (UDC) to an SDAP header in a PDCP-layer device according to anembodiment of the disclosure;

FIG. 2O is a view for proposing and explaining a method of generating anSDAP header for data received from an upper layer and not applying auser data compression (UDC) procedure to the SDAP header in a PDCP-layerdevice according to an embodiment of the disclosure;

FIG. 2P is a view for proposing and explaining a method of generating anSDAP header for data received from an upper layer in a PDCP-layer deviceand not applying encryption to a UDC header without applying a user datacompression (UDC) procedure to the SDAP header in a PDCP-layer deviceaccording to an embodiment of the disclosure;

FIG. 2Q is a view illustrating the processing gain that can be obtainedin a base station and a terminal implementation in an SDAP/PDCP-layerdevice or a bearer or a logical channel in which UDC is configured whenapplying an unencrypted SDAP header without user data compression andapplying an unencrypted UDC header, according to an embodiment of thedisclosure;

FIG. 2R is a view illustrating the operation of a transmittingSDAP/PDCP-layer device and a receiving SDAP/PDCP-layer device in theSDAP/PDCP-layer device or the bearer or logical channel in which the UDCis configured when applying unencrypted SDAP header without user datacompression and applying an unencrypted UDC header, according to anembodiment of the disclosure;

FIG. 2S is a view illustrating the configuration of a terminal accordingto an embodiment of the disclosure;

FIG. 2T is a view illustrating the configuration of a base stationaccording to an embodiment of the disclosure;

FIG. 3A is a view illustrating the structure of an LTE system accordingto an embodiment of the disclosure;

FIG. 3B is a view illustrating a radio protocol structure in an LTEsystem according to an embodiment of the disclosure;

FIG. 3C is a view illustrating the structure of a next-generation mobilecommunication system according to an embodiment of the disclosure;

FIG. 3D is a view for explaining new functions for handling QoS in an NRsystem according to an embodiment of the disclosure;

FIG. 3EA is a view illustrating a protocol stack including SDAP in NRaccording to an embodiment of the disclosure;

FIG. 3EB is a view showing a protocol stack including SDAP in NRaccording to an embodiment of the disclosure;

FIG. 3F is a view for explaining problems and issues when a first packetof a new QoS flow in a specific DRB is received in a delayed manner,considered in an embodiment of the disclosure;

FIG. 3G is a view for explaining a method of preferentially processing acorresponding SDAP packet when a new QoS flow is received in thereceiving SDAP layer of the terminal according to Embodiment 3-1 of thedisclosure;

FIG. 3H is a view illustrating a method for guaranteeing in-sequencedelivery at a receiving end when QoS flow is re-mapped according toEmbodiment 3-2 of the disclosure;

FIG. 3I is a view illustrating a method for delivering a new QoS flowpacket when QoS flow and mapping change of DRB are performed accordingto an embodiment of the disclosure;

FIG. 3J is a view illustrating overall terminal operation according toan embodiment of the disclosure;

FIG. 3K is a view illustrating the configuration of a terminal accordingto an embodiment of the disclosure; and

FIG. 3L is a view illustrating the configuration of an NR base stationaccording to an embodiment of the disclosure.

DETAILED DESCRIPTION

Hereinafter, the operation principle of the disclosure will be describedin detail in conjunction with the accompanying drawings. In thefollowing description of the disclosure, a detailed description of knownfunctions or configurations incorporated herein will be omitted when itmay make the subject matter of the disclosure rather unclear. The termswhich will be described below are terms defined in consideration of thefunctions in the disclosure, and may be different according to users,intentions of the users, or customs. Therefore, the definitions of theterms should be made based on the contents throughout the specification.

In the following description of the disclosure, a detailed descriptionof known functions or configurations incorporated herein will be omittedwhen it may make the subject matter of the disclosure rather unclear.

In the following description, terms for identifying access nodes, termsreferring to network entities, terms referring to messages, termsreferring to interfaces between network entities, terms referring tovarious identification information, and the like are illustratively usedfor the sake of convenience. Therefore, the disclosure is not limited bythe terms as used below, and other terms referring to subjects havingequivalent technical meanings may be used.

In the following description, the disclosure uses terms and namesdefined in 3rd generation partnership project long term evolution (3GPPLTE) standards for the convenience of description. However, thedisclosure is not limited by these terms and names, and may be appliedin the same way to systems that conform other standards. In thedisclosure, the term “eNB” may be interchangeably used with the term“gNB”. That is, a base station described as “eNB” may indicate “gNB”.

First Embodiment

FIG. 1A is a view illustrating the structure of a next-generation mobilecommunication system.

Referring to FIG. 1A, as illustrated, the radio access network of thenext-generation (new-radio (NR)) mobile communication system is composedof a next-generation base station (new-radio node B, hereinafter “gNB”)1 a-10 and a new-radio core network (AMF) 1 a-05. A user terminal(new-radio user equipment, hereinafter, “NR UE” or “terminal”) 1 a-15 isconnected to an external network via the gNB 1 a-10 and the AMF 1 a-05.

In FIG. 1A, the gNB 1 a-10 corresponds to the evolved node B (eNB) 1a-30 of the existing LTE system. The gNB 1 a-10 is connected to the NRUE 1 a-15 via a radio channel, and can provide service superior to thatof the existing Node B 1 a-20. In the next-generation mobilecommunication system, since all user traffic is served via a sharedchannel, a device for performing scheduling by collecting stateinformation, such as the buffer state of the UEs, available transmissionpower state, and channel state, is required, and the gNB 1 a-10 is incharge thereof. One gNB usually controls multiple cells. In order toimplement ultra-high speed data transmission compared to the existingLTE, bandwidth wider than the existing maximum bandwidth may besupported, and an orthogonal frequency-division multiplexing(hereinafter referred to as “OFDM”) method may be additionally appliedthe beamforming technology using radio access technology. In addition,an adaptive modulation and coding (hereinafter referred to as AMC)method for determining the modulation scheme and the channel-coding rateaccording to the channel condition of a terminal is applied. The AMF 1a-05 performs functions such as mobility support, bearer configuration,and QoS configuration. The AMF 1 a-05 is a device that is responsiblefor various control functions as well as mobility management functionsfor a terminal, and is connected to multiple base stations. In addition,the next-generation mobile communication system may be linked with anexisting LTE system, and the AMF 1 a-05 may be connected to an MME 1a-25 through a network interface. The MME 1 a-25 is connected to theexisting base station eNB 1 a-30. The terminal 1 a-15 supporting LTE-NRdual connectivity can transmit and receive data, while maintaining aconnection to the eNB 1 a-30 as well as the gNB 1 a-10 (1 a-35).

FIG. 1B is a view for explaining wireless connection state transition ina next-generation mobile communication system according to an embodimentof the disclosure.

In the existing LTE system, there are two wireless connection modes,namely a connected mode (or RRC connected mode) 1 b-35 and an idle mode(or RRC idle mode) 1 b-45. Switching between the two modes (1 b-40) isperformed via an establishment procedure and a release procedure.

In contrast, the next-generation mobile communication system has threewireless connection (RRC) states. The connected mode (or RRC_CONNECTED)1 b-05 is a wireless connection state in which a terminal can transmitand receive data. The idle mode (or RRC_IDLE) 1 b-30 is a wirelessaccess state in which the terminal monitors whether paging istransmitted to itself. The two modes are radio access states that arealso applied to the existing LTE system, and the detailed technology isthe same as that of the existing LTE system. In the next-generationmobile communication system, an inactive mode (RRC_INACTIVE) 1 b-15radio access state has been newly defined. In this radio access state,the UE context is maintained at the base station and the terminal, andRAN-based paging is supported. The characteristics of the new wirelessconnection state are as follows.

-   -   Cell re-selection mobility;    -   CN-NR RAN connection (both C/U-planes) has been established for        UE;    -   The UE AS context is stored in at least one gNB and the UE;    -   Paging is initiated by NR RAN;    -   RAN-based notification area is managed by NR RAN;    -   NR RAN knows the RAN-based notification area to which the UE        belongs

The new INACTIVE wireless connection state may transition to aconnection mode or a standby mode using a specific procedure. Dependingon the connection activation, it is switched from an INACTIVE mode to aconnected mode, and it is switched from the connected mode to theINACTIVE mode using the connection inactivation procedure (1 b-10). Theconnection activation/inactivation procedure is characterized in thatone or more RRC messages are transmitted and received between theterminal and the base station, and consist of one or more steps. It isalso possible to switch from an INACTIVE mode to a standby modeaccording to a specific procedure (1 b-20). Various methods such asspecific message exchange or timer-based or event-based methods may beconsidered as the above-mentioned specific procedure. Switching betweenthe connected mode and the standby mode can follow the existing LTEtechnology. That is, switching between the modes may be performedthrough a connection establishment or release procedure (1 b-25).

FIG. 1C is a view for explaining a phenomenon in which a radio accessstate is inconsistent in an LTE system according to an embodiment of thedisclosure.

The terminal 1 c-50 is in a connected state with a base station 1 c-10(1 c-15). The base station 1 c-10 transmits an RRC connection releasemessage to the terminal 1 c-05 in order to transit the terminal 1 c-05to an idle mode. However, the radio channel is not good, and theterminal 1 c-05 might not receive the message (1 c-20). In the existingstandard technology, the base station 1 c-10 does not wait for hybridautomatic repeat request (HARQ) feedback for the message, andimmediately assumes that the terminal 1 c-05 has been switched to theidle mode (1 c-30). Conversely, since the terminal 1 c-05 has notreceived the release message, the terminal 1 c-05 still maintains theconnected mode (1 c-25).

FIG. 1D is a view for explaining a method of dealing with a phenomenonin which a radio access state is inconsistent in an LTE system accordingto an embodiment of the disclosure.

In order to solve the above-described problem, one timer,DataInactivityTimer, is introduced in the LTE system. The timer isprovided to a terminal 1 d-05 using dedicated signaling. For example, abase station 1 d-10 may include the timer information in the RRCconnection setup message in the establishment procedure and provide thesame to the terminal 1 d-05 (1 d-15). Upon receiving the timerinformation, the terminal 1 d-05 drives the timer (1 d-20). The timerrestarts whenever data occurs in the uplink and downlink (1 d-25). Ifthe timer expires, the terminal 1 d-05 automatically switches to theidle mode (1 d-40). This solves the problem of inconsistency in theradio access state that may occur due to the terminal 1 d-05 notreceiving the release message (1 d-35). Therefore, both the terminal 1d-05 and the base station 1 d-10 are in the idle mode (1 d-45, 1 d-50).

An embodiment of the disclosure is characterized in that the RRC stateto which the terminal should switch or the action to be performed isconfigured together with the existing DataInactivityTimer when the timerexpires. In the next-generation mobile communication system, the RRCconnection release message can be used to switch the connected-stateterminal to the standby mode or the inactive mode. Therefore, when thetimer expires, it may be effective to configure the RRC state to whichto switch according to the intention of the network, rather than beingswitched to a fixed RRC state. For example, it is possible to minimizethe signaling overhead that is required when switching back to theconnected mode by switching to the inactive mode rather than batchswitching to the idle mode.

In Embodiment 1-1, when DataInactivityTimer expires, the RRC state towhich the terminal should switch is configured.

The network configures the timer for the terminal, and also configuresthe RRC state to which to switch when the timer expires. If the RRCstate is an inactive mode, the network may provide parameters related tothe inactive mode. The parameters may be I-RNTI, paging areaconfiguration, and the like. Here, I-RNTI is an indicator fordistinguishing between terminals in an inactive mode, and the pagingarea configuration is area information of a cell unit or a specific cellgroup unit in which paging provided to the terminal is transmitted. Ifthe RRC state to which to switch is the standby mode, the network sendsan RRC connection release message and then switches to the standby mode.After the timer expires, the terminal switches to the standby mode. Ifthe RRC state to which to switch is an inactive mode, the network sendsan RRC connection release message and then switches to the inactivemode. After the timer expires, the terminal switches to the inactivemode. If the RRC state to which to switch is an active mode and theparameters related to the inactive mode are not provided from thenetwork, the terminal performs RRC connection establishment afterreleasing the existing connection in order to acquire the parameters.After transmitting the RRC connection release message, the networkswitches to the inactive mode, but responds to RRC connectionestablishment by the terminal.

In Embodiment 1-2, the operation that the terminal should perform whenDataInactivityTimer expires is configured.

The network configures the timer for the terminal, and also configuresthe operation to be performed when the timer expires. If the operationto be performed is to switch to the standby mode, the network sends anRRC connection release message and then switches to the standby mode.After the timer expires, the terminal switches to the standby mode. Ifthe operation to be performed is RRC connection establishment, theterminal performs RRC connection establishment after the timer expires.After transmitting the RRC connection release message, the networkswitches to the inactive mode, but responds to the RRC connectionestablishment of the terminal.

When dual connectivity is configured to transmit and receive data byconnecting to multiple base stations, the DataInactivityTimerconfiguration is applied only to the MAC layer that manages the mastereNB (MeNB). That is, if data transmission to the MeNB does not occuruntil the timer expires, the terminal performs the operation. On theother hand, if the data transmission to the secondary eNB (SeNB) doesnot affect the start or restart of the timer, or if the datatransmission connected to the SeNB does not occur until the timerexpires, the terminal does not perform the operation, and merelyrestarts the timer.

FIG. 1E is a flowchart of a process for dealing with a phenomenon inwhich a wireless connection state is inconsistent according to anembodiment of the disclosure.

A terminal 1 e-05 camps on one cell 1 e-15. The terminal 1 e-05 performsRRC connection establishment with a base station 1 e-10 (1 e-20). In theabove process, a dedicated control channel (DCCH) 1 and a signalingradio bearer 1 (SRB) are configured. The base station 1 e-10 configuresDCCH 2 and SRB 2 for the terminal 1 e-05 using the RRC connectionreconfiguration message, and configures a dedicated traffic channel(DTCH) and DRB (1 e-25). The terminal transmits and receives data to andfrom the base station through the established logical channel and radiobearer. A medium access control (MAC) layer receives or transmits a MACservice data unit (SDU) through the DCCH or DTCH.

At this time, the base station 1 e-10 uses the RRC connectionreconfiguration message to the terminal 1 e-05 to configure theDataInactivityTimer and the RRC state to which the terminal 1 e-05should switch or the action to be performed (1 e-35). The configurationmay be provided to the terminal 1 e-05 in the RRC connectionestablishment process as well as RRC connection reconfiguration. Afterconfiguration, the terminal 1 e-05 starts a timer, and restarts thetimer whenever data transmission/reception occurs (1 e-45). If the RRCconnection release message transmitted by the network is lost in thewireless transmission section (1 e-55) and the timer expires, theterminal 1 e-05 checks the configured RRC state to which to switch orthe action to be performed (1 e-50). Depending on the RRC state to whichto switch or the operation to be performed, the operations of Embodiment1-1 or Embodiment 1-2 are performed. In the end, the terminal 1 e-05 andthe base station 1 e-10 maintain the same RRC state (1 e-60, 1 e-65).

FIG. 1F is a flowchart showing the operation of a terminal according toan embodiment of the disclosure.

In operation 1 f-05, a terminal performs RRC connection establishmentwith a base station.

In operation 1 f-10, the terminal switches to the connected mode.

In operation 1 f-15, the terminal receives a DataInactivityTimer and anRRC state that the UE needs in order to switch or an operation to beperformed from the BS.

In operation 1 f-20, the terminal starts a timer after theconfiguration, and restarts the timer whenever datatransmission/reception occurs.

When the timer expires in operation 1 f-25, the terminal identifies theconfigured RRC state to which to switch or an operation to be performed.Depending on the RRC state to which to switch or the operation to beperformed, the operations of Embodiment 1-1 or Embodiment 1-2 areperformed.

FIG. 1G is a flowchart showing the operation of a base station accordingto an embodiment of the disclosure.

In operation 1 g-05, a base station performs RRC connectionestablishment with a terminal.

In operation 1 g-10, the base station recognizes that the terminal isswitched to the connected mode.

In operation 1 g-15, the base station configures the DataInactivityTimerand the RRC state to which the terminal should switch, or the operationto be performed, for the terminal.

In operation 1 g-20, the base station transmits an RRC connectionrelease message to the terminal.

In operation 1 g-25, the base station switches the terminal to aspecific RRC state after a certain time. If the base station configuresthe standby mode as the RRC state to which the terminal should switch,the base station transmits the RRC message, and after a specific time,the terminal switches to the standby mode. If the base stationconfigures the inactive mode as the RRC state to which the terminalshould switch, the base station transmits the RRC message, and after acertain time, the terminal is switched to the inactive mode.

FIG. 1H is a view illustrating the configuration of a terminal accordingto an embodiment of the disclosure.

Referring to FIG. 1H, the terminal includes a radio-frequency (RF)processor 1 h-10, a baseband processor 1 h-20, a storage unit 1 h-30,and a controller 1 h-40. The controller 1 h-40 may include amultiple-connection processor 1 h-42.

The RF processor 1 h-10 performs a function for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 1 h-10up-converts a baseband signal provided from the baseband processor 1h-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 1 h-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital-to-analog converter (DAC), ananalog-to-digital converter (ADC), etc. In FIG. 1H, although only oneantenna is illustrated, the terminal may have multiple antennas. Also,the RF processor 1 h-10 may include a plurality of RF chains.Furthermore, the RF processor 1 h-10 may perform beamforming. For thebeamforming, the RF processor 1 h-10 may adjust the phase and magnitudeof each of signals transmitted and received through multiple antennas orantenna elements. In addition, the RF processor may perform MIMO, andmay receive multiple layers when performing MIMO operations.

The baseband processor 1 h-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical-layerstandard of a system. For example, during data transmission, thebaseband processor 1 h-20 generates complex symbols by encoding andmodulating a transmission bit stream. In addition, upon receiving data,the baseband processor 1 h-20 restores the received bit stream throughdemodulation and decoding of the baseband signal provided from the RFprocessor 1 h-10. For example, in the case of conforming to anorthogonal frequency-division multiplexing (OFDM) method, whentransmitting data, the baseband processor 1 h-20 encodes and modulates atransmission bit stream to generate complex symbols, maps the complexsymbols to subcarriers, and then configures OFDM symbols via an inversefast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. In addition, when receiving data, the baseband processor 1h-20 divides the baseband signal provided from the RF processor 1 h-10into units of OFDM symbols, restores signals mapped to subcarriers viathe fast Fourier transform (FFT) operation, and then restores a receivedbit stream via demodulation and decoding.

The baseband processor 1 h-20 and the RF processor 1 h-10 transmit andreceive signals as described above. Accordingly, each of the basebandprocessor 1 h-20 and the RF processor 1 h-10 may be referred to as atransmitter, a receiver, a transceiver, or a communicator. Furthermore,at least one of the baseband processor 1 h-20 and the RF processor 1h-10 may include a plurality of communication modules to support aplurality of different radio access technologies. In addition, at leastone of the baseband processor 1 h-20 and the RF processor 1 h-10 mayinclude different communication modules to process signals in differentfrequency bands. For example, the different radio access technologiesmay include a wireless LAN (e.g., IEEE 802.11), a cellular network(e.g., LTE), and the like. In addition, the different frequency bandsmay include a super-high-frequency (SHF) (e.g., 2.NRHz, NRhz) band and amillimeter-wave (e.g., 60 GHz) band.

The storage unit 1 h-30 stores data such as a basic program, anapplication, or configuration information for the operation of theterminal. In particular, the storage unit 1 h-30 may store informationrelated to the second access node, which performs wireless communicationusing the second wireless access technology. The storage unit 1 h-30provides stored data in response to a request from the controller 1h-40.

The controller 1 h-40 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 1 h-40 transmits and receives signals through the basebandprocessor 1 h-20 and the RF processor 1 h-10. In addition, thecontroller 1 h-40 records and reads data in the storage unit 1 h-30. Tothis end, the controller 1 h-40 may include at least one processor. Forexample, the controller 1 h-40 may include a communication processor(CP) that performs control for communication and an applicationprocessor (AP) that controls an upper layer such as an application.

FIG. 1I is a view illustrating the configuration of a base stationaccording to an embodiment of the disclosure.

The base station includes an RF processor 1 i-10, a baseband processor 1i-20, a backhaul communicator 1 i-30, a storage unit 1 i-40, and acontroller 1 i-50.

The RF processor 1 i-10 performs a function for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 1 i-10up-converts a baseband signal provided from the baseband processor 1i-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 1 i-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital-to-analog converter (DAC), ananalog-to-digital converter (ADC), etc. In FIG. 1I, although only oneantenna is illustrated, the first connection node may have multipleantennas. Also, the RF processor 1 i-10 may include a plurality of RFchains. Furthermore, the RF processor 1 i-10 may perform beamforming.For the beamforming, the RF processor 1 i-10 may adjust the phase andmagnitude of each of signals transmitted and received through multipleantennas or antenna elements. The RF processor may perform down-MIMOoperations by transmitting one or more layers.

The baseband processor 1 i-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical layerstandard of a first radio access technology. For example, during datatransmission, the baseband processor 1 i-20 generates complex symbols byencoding and modulating a transmission bit stream. In addition, uponreceiving data, the baseband processor 1 i-20 restores the received bitstream through demodulation and decoding of the baseband signal providedfrom the RF processor 1 i-10. For example, in the case of conforming tothe OFDM method, when transmitting data, the baseband processor 1 i-20encodes and modulates a transmission bit stream to generate complexsymbols, maps the complex symbols to subcarriers, and then configuresOFDM symbols via an inverse fast Fourier transform (IFFT) operation andcyclic prefix (CP) insertion. In addition, when receiving data, thebaseband processor 1 i-20 divides the baseband signal provided from theRF processor 1 i-10 into units of OFDM symbols, restores signals mappedto subcarriers via the FFT operation, and then restores a received bitstream via demodulation and decoding. The baseband processor 1 i-20 andthe RF processor 1 i-10 transmit and receive signals as described above.Accordingly, each of the baseband processor 1 i-20 and the RF processor1 i-10 may be referred to as a transmitter, a receiver, a transceiver,or a wireless communicator.

The backhaul communicator 1 i-30 provides an interface for performingcommunication with other nodes in a network. That is, the backhaulcommunicator 1 i-30 converts a bit stream transmitted from the basestation to another node, for example, an auxiliary base station or acore network, into a physical signal, and converts the physical signalreceived from the other node into a bit stream.

The storage unit 1 i-40 stores data such as a basic program, anapplication, and configuration information for the operation of the basestation. In particular, the storage unit 1 i-40 may store information onbearers allocated to the connected terminal, measurement resultsreported from the connected terminal, and the like. In addition, thestorage unit 1 i-40 may store information serving as a criterion fordetermining whether to provide or stop multiple connections to theterminal. Then, the storage unit 1 i-40 provides stored data in responseto a request from the controller 1 i-50.

The controller 1 i-50 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 1 i-50 transmits and receives signals through the basebandprocessor 1 i-20 and the RF processor 1 i-10 or through the backhaulcommunicator 1 i-30. In addition, the controller 1 i-50 records andreads data in the storage unit 1 i-40. To this end, the controller 1i-50 may include at least one processor.

Second Embodiment

FIG. 2A is a view illustrating the structure of an LTE system accordingto an embodiment of the disclosure.

Referring to FIG. 2A, as illustrated, the wireless access network of theLTE system is composed of next-generation base stations (evolved node B,hereinafter ENB, Node B or base station) 2 a-05, 2 a-10, 2 a-15, and 2a-20, a mobility management entity (MME) 2 a-25, and a serving gateway(S-GW) 2 a-30. A user equipment (hereinafter, UE or terminal) 2 a-35 isconnected to an external network through the ENB 2 a-05, 2 a-10, 2 a-15,and 2 a-20 and the S-GW 2 a-30.

In FIG. 2A, the ENBs 2 a-05, 2 a-10, 2 a-15, and 2 a-20 correspond tothe existing node B of a UMTS system. The ENB 2 a-05 is connected to theUE 2 a-35 by a wireless channel, and performs a more complicated rolethan the existing Node B. In the LTE system, since all user trafficincluding real-time services such as Voice over IP (VoIP), carried overthe Internet protocol, are served through a shared channel, a device isrequired to perform scheduling by collecting status information such asbuffer status, available transmission power status, and channel statusof UEs, and the ENBs 2 a-05, 2 a-10, 2 a-15, and 2 a-20 are responsibletherefor.

One ENB usually controls multiple cells. For example, in order torealize a transmission rate of 100 Mbps, the LTE system uses orthogonalfrequency-division multiplexing (OFDM) in, for example, a 20 MHzbandwidth as a radio access technology. In addition, an adaptivemodulation and coding (hereinafter, referred to as AMC) method isapplied to determine the modulation scheme and the channel-coding rateaccording to the state of a channel used by a terminal. The S-GW 2 a-30is a device that provides a data bearer, and creates or removes a databearer under the control of the MME 2 a-25. The MME 2 a-25 is a devicethat is responsible for various control functions as well as mobilitymanagement functions for the terminals 2 a-35, and is connected tomultiple base stations 2 a-05, 2 a-10, 2 a-15, and 2 a-20.

FIG. 2B is a view illustrating the structure of a wireless protocol ofan LTE system according to an embodiment of the disclosure.

Referring to FIG. 2B, the wireless protocol of the LTE system iscomposed of a packet data convergence protocol (PDCP) 2 b-05 and 2 b-40,a radio link control (RLC) 2 b-10 and 2 b-35, and a medium accesscontrol (MAC) 2 b-15 and 2 b-30, in a terminal and ENB. The packet dataconvergence protocols (PDCPs) 2 b-05 and 2 b-40 are responsible for IPheader compression/restoration. The main functions of the PDCP aresummarized as follows.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper-layer PDUs at PDCP        re-establishment procedure for RLC AM    -   For split bearers in DC (only support for RLC AM): PDCP PDU        routing for transmission and PDCP PDU reordering for reception    -   Duplicate detection of lower-layer SDUs at PDCP re-establishment        procedure for RLC AM    -   Retransmission of PDCP SDUs at handover and, for split bearers        in DC, of PDCP PDUs at PDCP data recovery procedure, for RLC AM    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

The radio link control (hereinafter, referred to as RLC) 2 b-10 and 2b-35 reconfigures the PDCP packet data unit (PDU) to an appropriate sizeto perform an automatic repeat request (ARQ) operation. The mainfunctions of the RLC are summarized as follows.

-   -   Transfer of upper-layer PDUs    -   Error Correction through ARQ (only for AM data transfer)    -   Concatenation, segmentation and reassembly of RLC SDUs (only for        UM and AM data transfer)    -   Re-segmentation of RLC data PDUs (only for AM data transfer)    -   Reordering of RLC data PDUs (only for UM and AM data transfer    -   Duplicate detection (only for UM and AM data transfer)    -   Protocol error detection (only for AM data transfer)

-   RLC SDU discard (only for UM and AM data transfer)

-   RLC re-establishment

The MACs 2 b-15 and 2 b-30 are connected to various RLC-layer devicesconfigured in a terminal or a base station, and perform operations ofmultiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MACPDUs. The main functions of MAC are summarized as follows.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TB)        delivered to/from the physical layer on transport        channels—Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification function    -   Transport format selection function    -   Padding function

The physical layers 2 b-20 and 2 b-25 channel-code and modulate theupper-layer data, convert the same into an OFDM symbol and transmit thesame to a radio channel, or demodulate and channel decode an OFDM symbolreceived through the radio channel and transmit the same to the upperlayer.

FIG. 2C is a view illustrating the structure of a next-generation mobilecommunication system according to an embodiment of the disclosure.

Referring to FIG. 2C, the radio access network of the next-generationmobile communication system (hereinafter, referred to as NR or 5G)includes a next-generation base station (new-radio Node B, NR gNB or NRbase station) 2 c-10 and new-radio core network (NR CN) 2 c-05. The userterminal (new-radio user equipment, NR UE or terminal) 2 c-15 accessesthe external network through the NR gNB 2 c-10 and the NR CN 2 c-05.

In FIG. 2C, the NR gNB 2 c-10 corresponds to an evolved node B (eNB) ofan existing LTE system. The NR gNB 2 c-10 is connected to the NR UE 2c-15 through a wireless channel and can provide superior service thanthe existing Node B. In the next-generation mobile communication system,since all user traffic is served through a shared channel, a device isrequired to collect and schedule status information such as bufferstatus of UEs, available transmission power status, and channel status,and the NR NB 2 c-10 is responsible therefor. One NR gNB usuallycontrols multiple cells. In order to implement ultra-high-speed datatransmission compared to the current LTE, more than the existing maximumbandwidth may be provided, and orthogonal frequency-divisionmultiplexing (OFDM) radio access technology may be additionally combinedwith beamforming technology. In addition, an adaptive modulation andcoding (hereinafter, referred to as AMC) method is applied to determinethe modulation scheme and the channel-coding rate according to the stateof a channel used by a terminal. The NR CN 2 c-05 performs functionssuch as mobility support, bearer setup, and QoS configuration. The NR CN2 c-05 is a device that is responsible for various control functions aswell as mobility management functions for a terminal, and is connectedto multiple base stations. In addition, the next-generation mobilecommunication system can be linked with the existing LTE system, and theNR CN 2 c-05 is connected to the MME 2 c-25 through a network interface.The MME 2 c-25 is connected to the existing base station eNB 2 c-30.

FIG. 2D is a view illustrating the structure of a wireless protocol of anext-generation mobile communication system according to an embodimentof the disclosure.

Referring to FIG. 2D, the wireless protocol structure of anext-generation mobile communication system is composed of an NR SDAP 2d-01, 2 d-45, NR PDCP 2 d-05, 2 d-40, an NR RLC 2 d-10, 2 d-35, and anNR MAC 2 d-15, 2 d-30 in a terminal and an NR base station,respectively.

The main functions of the NR SDAPs 2 d-01 and 2 d-45 may include some ofthe following functions.

-   -   Transfer of user-plane data    -   Mapping between a QoS flow and a DRB for both DL and UL    -   Marking QoS flow ID in both DL and UL packets    -   Mapping reflective QoS flow to DRB for the UL SDAP PDUs

For the SDAP-layer device, the UE can be configured with regard towhether to use the header of the SDAP-layer device or the function ofthe SDAP-layer device for each PDCP-layer device, for each bearer, orfor each logical channel through an RRC message, and when the SDAPheader is configured, the NAS QoS reflection configuration 1-bitindicator (NAS reflective QoS) of the SDAP header and the AS QoSreflection configuration 1-bit indicator (AS reflective QoS) mayindicate that the terminal can update or reset the QoS flow of uplinkand downlink and mapping information for the data bearer. The SDAPheader may include QoS flow ID information indicating QoS. The QoSinformation may be used as data-processing priority and schedulinginformation to support smooth service.

The main functions of the NR PDCP 2 d-05, 2 d-40 may include some of thefollowing functions.

-   -   Header compression and decompression: ROHC only    -   Transfer user data    -   In-sequence delivery of upper-layer PDUs    -   Out-of-sequence delivery of upper-layer PDUs    -   PDCP PDU reordering for reception    -   Duplicate detection of lower-layer SDUs    -   Retransmission of PDCP SDUs    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

In the above, reordering function of the NR PDCP device (reordering)refers to a function of reordering PDCP PDUs received from a lower layerin order based on PDCP sequence numbers (SN), and may includetransmitting data to an upper layer in a reordered order, or may includea function for immediately transmitting without consideration of theorder, may include a function for reordering the order to record thelost PDCP PDUs, may include a function for sending a status report forthe lost PDCP PDUs to the transmitting side, and may include a functionfor requesting retransmission for lost PDCP PDUs.

The main functions of the NR RLCs 2 d-10 and 2 d-35 may include some ofthe following functions.

-   -   Transfer of upper-layer PDUs    -   In-sequence delivery of upper-layer PDUs    -   Out-of-sequence delivery of upper-layer PDUs    -   Error Correction through ARQ    -   Concatenation, segmentation and reassembly of RLC SDUs    -   Re-segmentation of RLC data PDUs    -   Reordering of RLC data PDUs    -   Duplicate detection    -   Protocol error detection    -   RLC SDU discard    -   RLC re-establishment

In the above, the in-sequence delivery of the NR RLC device refers to afunction of sequentially transmitting RLC SDUs received from a lowerlayer to an upper layer. Originally, when one RLC SDU is received bybeing divided into several RLC SDUs, it may include a function ofreassembling and transmitting the same, may include a function ofrearranging the received RLC PDUs based on an RLC sequence number (SN)or a sequence number (PDCP SN), may include a function of rearrangingthe order to record the lost RLC PDUs, may include a function forsending a status report for the lost RLC PDUs to the transmitting side,and may include a function for requesting retransmission for the lostRLC PDUs. If there is a lost RLC SDU, it may include a function oftransmitting only the RLC SDUs up to the lost RLC SDU to the upper layerin sequence. Alternatively, even if there is a lost RLC SDU, if apredetermined timer has expired, a function of delivering all RLC SDUsreceived before the timer starts, in sequence, to an upper layer may beincluded. Alternatively, even if there is a lost RLC SDU, if apredetermined timer expires, a function of delivering all RLC SDUsreceived so far to the upper layer in sequence may be included. Inaddition, the RLC PDUs may be processed in the order in which they arereceived (regardless of the sequence number, in the order of arrival)and delivered to the PDCP device in any order (out-of-sequencedelivery). In the case of segments, segments that are stored in a bufferor that are to be received at a later time can be received,reconstructed into a complete RLC PDU, processed, and then delivered toa PDCP device. The NR RLC layer may not include a concatenationfunction, and the function may be performed in the NR MAC layer, or maybe replaced by a multiplexing function of the NR MAC layer.

In the above, out-of-sequence delivery of the NR RLC device refers to afunction of directly transmitting RLC SDUs received from a lower layerto an upper layer regardless of order. Originally, when one RLC SDU isdivided into multiple RLC SDUs and received, it may include a functionof reassembling and transmitting the same, and may include a function ofstoring the RLC SN or PDCP SN of the received RLC PDUs and arranging theorder to record the lost RLC PDUs.

The NR MACs 2 d-15 and 2 d-30 may be connected to various NR RLC-layerdevices configured in a terminal or a base station, and the mainfunction of the NR MAC may include some of the following functions.

Mapping Between Logical Channels and Transport Channels

-   -   Multiplexing/demultiplexing of MAC SDUs    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

The NR PHY layer 2 d-20, 2 d-25 may perform an operation ofchannel-coding and modulating upper-layer data, making an OFDM symboland transmitting the same on a radio channel, or demodulating andchannel-decoding an OFDM symbol received via the radio channel andtransmitting the same to an upper layer.

The embodiment of the disclosure proposes a procedure for compressingdata and decompressing the same at a base station when a terminaltransmits data in an uplink in a wireless communication system, andproposes a method for supporting a data transmission/reception procedurethat compresses and transmits data at a transmitting end, anddecompresses the same at a transmitting end, using, for example, aspecific header format and a resolution method, when decompressionfails. Also, the method proposed in the embodiment of the disclosure canbe applied to a procedure in which the base station compresses andtransmits data when the downlink data is transmitted to the terminal andthe terminal receives and decompresses the compressed downlink data. Inthe embodiment of the disclosure as described above, by compressing andtransmitting data at the transmitting end, it is possible to transmit alarger amount of data and improve coverage.

FIG. 2E is a view illustrating a procedure for configuring whether abase station performs uplink data compression when a terminalestablishes a connection with a network according to an embodiment ofthe disclosure.

FIG. 2E illustrates a procedure for a UE to establish a connection witha network by switching from an RRC idle mode or an RRC inactive mode (orlightly connected mode) to an RRC connected mode in the disclosure, anda procedure for configuring whether to perform uplink data compression(UDC).

In FIG. 2E, the base station may transmit the RRCConnectionReleasemessage to the terminal to switch the terminal to the RRC idle mode ifthe terminal, transmitting/receiving data in the RRC connection mode,does not transmit or receive data for a predetermined reason or for apredetermined time (2 e-01). In the future, a terminal that is notcurrently connected (hereinafter referred to as an “idle-mode UE”)performs an RRC connection establishment process with a base stationwhen there is data to be transmitted. The terminal performs reversetransmission synchronization with the base station via a random accessprocess and transmits an RRCConnectionRequest message to the basestation (2 e-05). The message includes the identifier of the terminaland the reason for establishing the connection (establishmentCause). Thebase station transmits an RRCConnectionSetup message so that theterminal establishes an RRC connection (2 e-10). The message may includeinformation indicating whether to use the uplink data compression method(UDC) for each logical channel (logicalchannelconfig), for each bearer,or for each PDCP device (PDCP-config). In addition, more specifically,it is possible to indicate which IP flow or QoS flow is to be used onlyfor uplink data compression (UDC) in each logical channel or bearer oreach PDCP device (or SDAP device). (By configuring the information onthe IP flow or QoS flow to use or not to use the uplink data compressionmethod for the SDAP device, the SDAP device may indicate to the PDCPdevice whether or not the SDCP device uses the uplink data compressionmethod for each QoS flow. Alternatively, the PDCP device may itselfidentify each QoS flow and decide whether or not to apply the uplinkcompression method.) In addition, if instructed to use the uplink datacompression method as above, through the message, an identifier for apredetermined library or dictionary to be used in the uplink datacompression method or the size of a buffer to be used in the uplink datacompression method may be indicated. Also, the message may include acommand to perform setup for uplink decompression or release the same.In addition, when the uplink data compression method is set to be used,the RLC AM bearer (ARQ function, lossless mode with retransmissionfunction) may always be used, and may not be configured together withthe header compression protocol (ROHC). In addition, the message mayindicate whether to use the function of the SDAP-layer device or theSDAP header for each logical channel (logicalchannelconfig), for eachbearer, or for each PDCP device (PDCP-config). In addition, the messagemay indicate whether to apply ROHC (P packet header compression) foreach logical channel (logicalchannelconfig), for each bearer, or foreach PDCP device (PDCP-config), and may configure whether to apply ROHCto each of the uplink and downlink as indicators. However, both ROHC andUDC cannot be configured for one PDCP-layer device or logical channel orbearer at the same time, and UDC can be configured for up to twobearers. In addition, the message may indicate whether integrityprotection is applied to each logical channel (logicalchannelconfig), toeach bearer, or to each PDCP device (PDCP-config), it can be configuredin consideration of the maximum data transmission rate of thecorresponding PDCP-layer device, or bearer, or logical channel. Also,RRC connection configuration information and the like may be stored inthe message. The RRC connection is also called signaling radio bearer(SRB), and is used to transmit and receive RRC messages, which arecontrol messages, between the terminal and the base station.

The terminal, having configured the RRC connection, transmits anRRCConnectionSetupComplete message to the base station (2 e-15). If thebase station does not know the capability of the terminal that iscurrently establishing the connection, or if it wants to know theterminal capability, it can send a message inquiring about thecapability of the terminal. In response thereto, the terminal can send amessage reporting the capabilities thereof. The message may indicatewhether the terminal can use uplink data compression (UDC), robustheader compression (ROHC), or integrity protection, and can betransmitted in the state of including an indicator indicating the same.The RRCConnectionSetupComplete message includes a control message calledSERVICE REQUEST in which the terminal requests the MME to set up abearer for a given service. The base station transmits the SERVICEREQUEST message received in the RRCConnectionSetupComplete message tothe MME (2 e-20), and the MME determines whether to provide the servicerequested by the terminal. As a result of the determination, if theterminal decides to provide the requested service, the MME sends amessage INITIAL CONTEXT SETUP REQUEST to the base station (2 e-25). TheINITIAL CONTEXT SETUP REQUEST message includes quality of service (QoS)information to be applied when configuring a data radio bearer (DRB),and security-related information (e.g., security key, securityalgorithm) to be applied to the DRB. The base station exchanges theSecurityModeCommand message (2 e-30) and the SecurityModeCompletemessage (2 e-35) to establish security configurations with the terminal.When the security configurations are established, the base stationtransmits an RRCConnectionReconfiguration message to the terminal (2e-40). The RRCConnectionReconfiguration message may include informationindicating whether to use the uplink data compression method (UDC) foreach logical channel (logicalchannelconfig), for each bearer, or foreach PDCP device (PDCP-config). In addition, more specifically, it ispossible to indicate whether to use an uplink data compression (UDC)method only for particular IP flow or QoS flow in each logical channelor bearer or each PDCP device (or SDAP device). (Information on IP flowand QoS flow to which the uplink data compression method is used or notused may be configured for the SDAP device, and the SDAP device mayindicate to the PDCP device whether or not the SDCP device uses theuplink data compression method to each QoS flow. Alternatively, the PDCPdevice may itself identify each QoS flow and determine whether or not toapply the uplink compression method.) In addition, if use of the uplinkdata compression method is indicated above, an identifier for apredetermined library or dictionary to be used in the uplink datacompression method or a buffer size to be used in the uplink datacompression method may be indicated through the message. Also, themessage may include a command to perform configuration for uplinkdecompression or to release the same. In addition, when configured touse the uplink data compression method in the above, the message canalways by configured as an RLC AM bearer (ARQ function, lossless modewith retransmission function), and might not be configured together withthe header compression protocol (ROHC). In addition, the message mayindicate whether to use the function of the SDAP-layer device or theSDAP header for each logical channel (logicalchannelconfig), for eachbearer, or for each PDCP device (PDCP-config), and the message mayindicate whether to apply ROHC (IP packet header compression) for eachlogical channel (logicalchannelconfig), for each bearer, or for eachPDCP device (PDCP-config), and whether to apply ROHC for uplink anddownlink can be configured as respective indicators. However, both ROHCand UDC cannot be configured for one PDCP-layer device or logicalchannel or bearer at the same time, and UDC can be configured for up totwo bearers. In addition, the message may indicate whether to applyintegrity verification for each logical channel (logicalchannelconfig),for each bearer, or for each PDCP device (PDCP-config), and may beconfigured in consideration of the maximum data transmission rate of thecorresponding PDCP layer, bearer, or logical channel. In addition, themessage includes the DRB setting information to be processed by the userdata, and the terminal applies the information to configure the DRB andtransmits an RRCConnectionReconfigurationComplete message to the basestation (2 e-45).

The base station, having completed the DRB setup with the terminal,sends an INITIAL CONTEXT SETUP COMPLETE message to the MME (2 e-50), andthe MME, upon receiving the same, exchanges the S1 BEARER SETUP messageand the S1 BEARER SETUP RESPONSE message to configure the S-GW and S1bearer (2 e-055, 2 e-60). The S1 bearer is a connection for datatransmission that is established between the S-GW and the base stationand corresponds one-to-one to the DRB. When all of the above processesare completed, the terminal transmits and receives data through the basestation and the S-GW (2 e-65, 2 e-70). This general data transmissionprocess is largely composed of three steps: RRC connectionconfiguration, security configuration, and DRB configuration.

In addition, the base station may transmit anRRCConnectionReconfiguration message in order to reconfigure, add, orchange configurations to the terminal for a predetermined reason (2e-75). The message may include information indicating whether to use theuplink data compression method (UDC) for each logical channel(logicalchannelconfig), for each bearer, or for each PDCP device(PDCP-config). In addition, more specifically, it is possible toindicate whether to use uplink data compression (UDC) only for an IPflow or a QoS flow in each logical channel or bearer or each PDCP device(or SDAP device). (By configuring the information on the IP flow or QoSflow, which uses or does not use the uplink data compression method forthe SDAP device, the SDAP device may indicate to the PDCP device whetheror not to use the uplink data compression method for each QoS flow.Alternatively, the PDCP device may itself check each QoS flow and decidewhether or not to apply the uplink compression method.) In addition, ifinstructed to use the uplink data compression method above, through themessage, an identifier for a predefined library or dictionaryinformation to be used in the uplink data compression method or a buffersize to be used in the uplink data compression method may be indicatedthrough the message. Also, the message may include a command to performsetup for uplink decompression or release the same. In addition, whenthe message is configured to use the uplink data compression method asabove, it may always be configured as an RLC AM bearer (lossless modewith ARQ function, retransmission function), and might not be configuredtogether with a header compression protocol (ROHC). In addition, themessage may indicate whether to use the function of the SDAP-layerdevice or the SDAP header for each logical channel(logicalchannelconfig), for each bearer, or for each PDCP device(PDCP-config), and the message may indicate whether to apply ROHC (IPpacket header compression) for each logical channel(logicalchannelconfig), for each bearer, or for each PDCP device(PDCP-config), and may configure whether or not to apply ROHC as anindicator for each of uplink and downlink. However, the ROHC and UDCcannot be configured for one PDCP-layer device, logical channel, orbearer at the same time, and the UDC can be configured for up to twobearers. In addition, the message may indicate whether to applyintegrity verification for each logical channel (logicalchannelconfig),for each bearer, or for each PDCP device (PDCP-config), and may indicateconfiguration in consideration of the maximum data transmission rate ofthe corresponding PDCP-layer device, bearer, or logical channel.

FIG. 2F is a view illustrating a procedure and data configuration forperforming uplink data compression according to an embodiment of thedisclosure.

In FIG. 2F, uplink data 2 f-05 may be produced as data corresponding toservices such as video transmission, picture transmission, web search,and VoLTE. The data produced in the application-layer device may beprocessed via TCP/IP or UDP, corresponding to the network data transportlayer, construct each header 2 f-10, 2 f-15, and may be transmitted tothe PDCP layer. When the PDCP layer receives data (PDCP SDU) from anupper layer, the following procedure can be performed.

If, in FIG. 2E, configuration is made to use the uplink data compressionmethod in the PDCP layer by the RRC message such as 2 e-10 or 2 e-40 or2 e-75, uplink data compression for the PDCP SDU as in 2 f-20 isperformed to compress uplink data, and a corresponding UDC header (aheader for compressed uplink data, 2 f-25) is constructed. If integrityprotection is configured, integrity protection may be performed,ciphering may be performed, and a PDCP PDU may be configured byconfiguring the PDCP header 2 f-30. In the above, the PDCP-layer deviceincludes a UDC compression/decompression device, determines whether ornot to perform the UDC procedure for each piece of data as configured inthe RRC message, and uses the UDC compression/decompression device. Thetransmitting end performs data compression using the UDC compressiondevice in the transmitting PDCP-layer device, and the receiving endperforms data decompression using the UDC decompression device in thereceiving PDCP-layer device.

The procedure of FIG. 2F described above can be applied when compressingdownlink data as well as when the terminal compresses uplink data. Inaddition, the description with regard to the uplink data can be appliedto the downlink data in the same way.

FIG. 2G is a view illustrating an embodiment of an uplink datacompression method according to an embodiment of the disclosure.

FIG. 2G is a view illustrating a description of a DEFLATE-based uplinkdata compression algorithm, and the DEFLATE-based uplink datacompression algorithm is a lossless compression algorithm. TheDEFLATE-based uplink data compression algorithm basically compressesuplink data by combining the LZ77 algorithm and Huffman coding. The LZ77algorithm performs an operation of searching for a duplicate array ofdata. When searching for duplicate arrays, if duplicate arrays are foundby searching for duplicate arrays through a sliding-window, the LZ77algorithm expresses the position and degree of overlapping of theduplicate arrays in the sliding window as lengths to perform datacompression. The sliding window is also called a buffer in the uplinkdata compression (UDC) method, and may be configured as 8 kilobytes or32 kilobytes. That is, the sliding window or buffer can performcompression by recording 8192 or 32768 characters, searching duplicatearrays, and expressing them by position and length. Therefore, since theLZ algorithm is a sliding-window method, that is, since previously codeddata is updated in a buffer, and coding is again performed on subsequentdata, there is a correlation between successive data. Therefore, thecoded data should be decoded normally, after which the data can bedecoded normally. The compressed codes (expression of position, length,etc.), expressed by position and length according to the LZ77 algorithm,are compressed once more via Huffman coding. Hoffman coding searches forduplicate codes again, and uses a short notation for codes with a highdegree of overlapping and a long notation for codes with a low degree ofoverlapping to perform compression once again. The Hoffman coding isprefix coding, and is an optimal coding scheme in which all codes aredistinctly decodable.

As described above, the transmitting end performs encoding by applyingthe LZ77 algorithm to the original data (2 g-05, 2 g-10), updates thebuffer (2 g-15), produces checksum bits for the contents (or data) ofthe buffer, and configures the same in the UDC header. The checksum bitsare used at the receiving end to determine whether the buffer status isvalid. Codes encoded with the LZ77 algorithm can be compressed onceagain with Huffman coding and transmitted as uplink data (2 g-25). Thereceiving end, rather than the transmitting end, performs thedecompression procedure on the received compressed data. That is, thereceiving end performs Hoffman decoding (2 g-30), updates the buffer (2g-35), and checks the validity of the updated buffer with checksum bitsin the UDC header. When it is determined that the checksum bits are noterror-free, decoding may be performed using the LZ77 algorithm (2 g-40)to decompress the data and restore the original data to be delivered tothe upper layer (2 g-45).

As described above, since the LZ algorithm is a sliding-window method,that is, since previously coded data is updated in a buffer, and codingis performed on immediately following data, successive data hascorrelation each other. Therefore, the coded data should be decodednormally, after which the data can be decoded normally. Therefore, thereceiving PDCP-layer device checks the PDCP serial number of the PDCPheader and checks the UDC header (checks the indicator indicatingwhether or not data compression has been performed) to perform a datacompression procedure in ascending order of PDCP serial number on thedata to which the data compression procedure has been applied.

FIG. 2H is a view illustrating a procedure and data configuration forperforming robust header compression (ROHC) according to an embodimentof the disclosure.

In FIG. 2H, the uplink data 2 h-05 may be generated as datacorresponding to services such as video transmission, picturetransmission, web search, and VoLTE. The data generated in theapplication-layer device is processed through TCP/IP or UDPcorresponding to the network data transport layer, may constructs eachheader 2 h-10 and 2 h-15, and may be transmitted to the PDCP layer. Whenthe PDCP layer receives data (PDCP SDU) from an upper layer, thefollowing procedure can be performed.

If, in FIG. 2E, configuration is made to use the uplink data compressionmethod in the PDCP layer via the RRC message, such as 2 e-10 or 2 e-40or 2 e-75, the header compression (ROHC) method may be performed for thePDCP SDU as in 2 h-20 to compress the header 2 h-15 of the receivedupper-layer data and generate compressed data 2 h-25. If integrityprotection is configured, integrity protection may be performed,ciphering may be performed, and a PDCP PDU may be configured byconfiguring the PDCP header 2 h-30. In the above, the PDCP-layer deviceincludes a header compression/decompression device, determines whetheror not to perform header compression for each piece of data asconfigured in the RRC message, and uses the headercompression/decompression device. The transmitting end performs datacompression using the header compression device in the transmittingPDCP-layer device, and the receiving end performs data decompressionusing the header decompression device in the receiving PDCP-layerdevice.

The procedure of FIG. 2H described above can be applied when compressingdownlink data as well as when the terminal compresses uplink data. Inaddition, the description with regard to the uplink data can be appliedto the downlink data in the same way.

FIG. 2I is a view illustrating a procedure for generating an SDAP headerfor data received from an upper layer and encrypting the SDAP header ina PDCP-layer device according to an embodiment of the disclosure.

In FIG. 2, when the SDAP-layer device is configured to use theSDAP-layer device function by the RRC message such as 2 e-10 or 2 e-40or 2 e-75 in FIG. 2e or is configured to use the SDAP header, whenreceiving data from the upper layer, the SDAP-layer device can generateand configure the SDAP header as in 2 i-05 and deliver the same to thePDCP-layer device. The PDCP-layer device performs integrity protectionwhen integrity verification is configured for the PDCP SDUs (SDAPheaders and IP packets, 2 i-10) received from the higher SDAP-layerdevice, performs encryption, generates and configures a PDCP header,joins the same, and sends the same to the lower layer to perform RLCdata processing in the RLC-layer device and the MAC-layer device.

FIG. 2J is a view of a procedure for generating an SDAP header for datareceived from an upper layer in a PDCP-layer device and not performingencryption on the SDAP header according to an embodiment of thedisclosure.

In FIG. 2J, when the SDAP-layer device is set to use the SDAP-layerdevice function by the RRC message such as 2 e-10 or 2 e-40 or 2 e-75 inFIG. 2e or is set to use the SDAP header, when receiving data from theupper layer, the SDAP-layer device may generate and configure the SDAPheader as in 2 j-05 and deliver the same to the PDCP-layer device. ThePDCP-layer device is characterized in that it encrypts only theremaining data (P packet) except the SDAP header for the PDCP SDU (SDAPheader and IP packet, 2 j-10) received from the upper SDAP-layer device.In addition, the PDCP-layer device is characterized in that, ifintegrity verification is configured, the integrity protection isperformed only on the remaining data except the SDAP header for the PDCPSDU (SDAP header and IP packet, 2 j-10) received from the upperSDAP-layer device. That is, if integrity verification is configured, thePDCP-layer device applies integrity protection to the rest of the data(P packet), other than the SDAP header for the PDCP SDU (SDAP header andIP packet, 2 j-10) received from the upper SDAP-layer device, performsencryption, and then produces, configures and joins the PDCP header andtransfers to the lower layer to perform data processing in the RLC-layerdevice and the MAC-layer device. If the SDAP header is not encrypted,the implementation of the base station structure can be facilitated, asdescribed above. In particular, if the SDAP header is not encrypted bythe CU in the split central unit (CU)/distributed unit (DU) structure,the SDAP header can be read from the DU and the QoS information can bechecked and applied to the scheduling, which is advantageous in matchingand adjusting QoS. There is also a benefit in terms of data processingin terminal and base-station implementations.

FIG. 2K is a view showing the gain in the structure of the base-stationimplementation when the unencrypted SDAP header according to theembodiment of the disclosure is applied.

As in FIG. 2K, in order to reduce initial facility costs and maintenancecosts in the implementation of a base station, upper-layer devices(e.g., a PDCP-layer device and upper-layer devices) may be implementedin a central unit (CU), and lower-layer devices (for example, anRLC-layer device and lower-layer devices) may be implemented in aplurality of distributed units (DUs) connected to the CU. In this CU-DUsplit structure, when the unencrypted SDAP header is applied by thePDCP-layer device 2 k-05 as proposed in FIG. 2j of the disclosure, theSDAP header is not encrypted, even in a plurality of DUs 2 k-15.Therefore, the SDAP header 2 k-10 can be read, and QoS information canbe checked and applied to scheduling of the DU. Therefore, the QoSinformation of the SDAP header can be used to allocate and scheduletransmission resources in the DU, so it can be advantageous to adjustand adjust QoS for each service.

FIG. 2L is a view illustrating processing gains that are obtained in abase station and a terminal implementation when an unencrypted SDAPheader according to an embodiment of the disclosure is applied.

In FIG. 2L, when implementing a terminal and a base station, SDAP-layerdevices and PDCP-layer devices can be integrated into a single-layerdevice (2 l-01). Since the SDAP-layer device is logically theupper-layer device of the PDCP-layer device, when receiving data (2l-05) from the upper application layer, if the SDAP-layer device isconfigured to use the SDAP-layer device function by an RRC message suchas 2 e-10 or 2 e-40 or 2 e-75 in FIG. 2E, or is configured to use theSDAP header, when receiving data from the upper layer, the SDAP headershould be generated and configured as indicated by 2 j-05 in FIG. 2J.However, in the implementation of the terminal and the base station, aciphering procedure or an integrity protection procedure is a highlycomplex operation, and can be implemented by applying a hardware (HW)accelerator. HW accelerators have high processing gains in repetitiveand continuous procedures. However, if the SDAP header is configuredwhenever the SDAP-layer device receives data from the upper-layerdevice, the encryption procedure is performed on the data portion,excluding the SDAP header, and the PDCP header is generated and attachedto the SDAP header, interruption may occur in the HW accelerator in theabove procedure, due to the procedure of generating the SDAP headerbefore performing encryption.

Accordingly, an embodiment of the disclosure proposes a method ofintegrating an SDAP-layer device and a PDCP-layer device into asingle-layer device in an implementation with an unencrypted SDAPheader. That is, when data is received from the upper application layer,the encryption procedure is continuously and repeatedly performed everytime data is received, and the PDCP header and SDAP header 2 l-10 may besimultaneously generated, to be bonded to the encrypted data, andtransmitted to the lower layer. Generation of the PDCP header and theSDAP header may be performed in parallel with the encryption procedure.When generating the headers in parallel, the SDAP header, the PDCPheader, or the RLC header or the MAC header may be generated together,and the headers may be joined at the beginning of the data processing toprepare for transmission (MAC PDU configuration may be prepared).

In addition, the receiving end separates the SDAP header, the PDCPheader, the UDC header, or the RLC header or the MAC header from thedata to read all at a time, identify all the information correspondingto each layer, and processes the data in the reverse order of dataprocessing at the transmitting end. Therefore, the HW accelerator can becontinuously and repeatedly applied, and there is no interruption suchas SDAP header generation in the middle, thereby increasing theefficiency of data processing. In addition, if integrity protection isconfigured, integrity protection may be repeatedly performed by applyinga hardware accelerator as described for the encryption procedure beforeperforming the encryption procedure. That is, integrity protection canbe applied and encryption can be performed.

As for the receiving PDCP-layer device, as in 2 l-01, a method ofimplement a single layer device by integrating the SDAP layer device andthe PDCP layer device can be applied. That is, when data is receivedfrom a lower layer (RLC layer), when the SDAP-layer device function isconfigured to be used by an RRC message such as 2 e-10 or 2 e-40 or 2e-75 in FIG. 2e , or when the SDAP header is configured to be used, thePDCP header and SDAP header can be read at once, the headers can beremoved, and a deciphering procedure can be repeatedly applied to data.In addition, when integrity protection is configured, integrityverification may be repeatedly performed by applying a hardwareaccelerator as described for the decryption procedure after performingthe decryption procedure. That is, decryption may be performed andintegrity verification may be performed.

FIG. 2M is a view illustrating processing gains that can be obtainedfrom a base station and a terminal implementation in which ROHC is setwhen an unencrypted SDAP header is applied according to an embodiment ofthe disclosure.

In FIG. 2M, when implementing a terminal and a base station, SDAP-layerdevices and PDCP-layer devices may be integrated into a single-layerdevice (2 m-01). Since the SDAP-layer device is logically theupper-layer device of the PDCP-layer device, when receiving data (2m-05) from the upper application layer, in the case in which theSDAP-layer device is configured to use the SDAP-layer device function oran SDAP header through an RRC message such as 2 e-10 or 2 e-40 or 2 e-75in FIG. 2e , when receiving data from the upper layer, the SDAP headershould be generated and configured as indicated by 2 j-05 in FIG. 2j .However, in the implementation of the terminal and the base station, theciphering procedure can be implemented by applying a hardware (HW)accelerator, because it is a highly complex operation. HW acceleratorshave high processing gains in repetitive and continuous procedures.However, if a process of configuring the SDAP header, performing theencryption procedure on the data portion excluding the SDAP header,generating the PDCP header, and attaching the same to the SDAP header isperformed whenever the SDAP-layer device receives data from theupper-layer device, it may interrupt the HW accelerator due to theprocedure of generating the SDAP header before performing encryption.

Therefore, the embodiment of the disclosure proposes a method forimplementing a single-layer device by integrating the SDAP-layer deviceand the PDCP-layer device in an implementation with an unencrypted SDAPheader in the case in which the ROHC is configured. That is, when datais received from the upper application layer, every time data isreceived, ROHC is applied to compress the data of the upper layer togenerate a compressed header (2 m-07), an encryption procedure iscontinuously and repeatedly performed, and the PDCP header and SDAPheader (2 m-10) can be generated at the same time to be joined to theencrypted data and transmitted to the lower layer. Generation of thePDCP header and the SDAP header can be performed in parallel with theencryption procedure. When generating the header in parallel, the SDAPheader, the PDCP header, the RLC header and the MAC header are generatedtogether, and headers may be joined at the beginning of the dataprocessing to prepare for transmission (MAC PDU configuration may beprepared). In addition, the receiving end may separate the SDAP header,the PDCP header, the UDC header, the RLC header, and the MAC header at atime to read all the information corresponding to each layer, andprocess the data in the reverse order of data processing at thetransmitting end. Therefore, the HW accelerator can be continuously andrepeatedly applied, and there is no interruption such as SDAP headergeneration in the middle, thereby increasing the efficiency of dataprocessing. In addition, if integrity protection is configured,integrity protection may be repeatedly performed by applying a hardwareaccelerator as described for the encryption procedure before performingthe encryption procedure. That is, integrity protection can be appliedand encryption can be performed.

As for the receiving PDCP-layer device, as in 2 m-01, a method ofintegrating the SDAP-layer device and the PDCP-layer device into asingle-layer device to implement a single-layer device can be applied inthe case in which the ROHC is configured. That is, when data is receivedfrom a lower layer (RLC layer), when the SDAP-layer device function isconfigured to be used by an RRC message such as 2 e-10 or 2 e-40 or 2e-75 in FIG. 2e or when the SDAP header is configured to be used, thePDCP header and SDAP header can be read and removed at once, adeciphering procedure can be repeatedly applied to data, and adecompression procedure may be performed on the upper-layer header (Ppacket header). In addition, when integrity protection is configured,integrity verification may be repeatedly performed by applying ahardware accelerator as described for the decryption procedure afterperforming the decryption procedure. That is, decryption may beperformed and integrity verification may be performed.

FIG. 2N is a view for explaining the generation of an SDCP header fordata received from an upper layer and application of a user datacompression procedure (UDC) to an SDAP header in a PDCP-layer device,according to an embodiment of the disclosure.

In FIG. 2N, when the SDAP-layer device is configured to use theSDAP-layer device function by using RRC messages such as 2 e-10 or 2e-40 or 2 e-75 in FIG. 2E, or is configured to use the SDAP header, andwhen user data compression (uplink data compression, UDC) is configured,when receiving data from the upper layer, the SDAP-layer device SDAPheader may generate and configure the SDAP header as indicated by 2 n-05and transfer the same to the PDCP-layer device. The PDCP-layer devicemay perform user data compression on the PDCP SDU (SDAP header and IPpacket, 2 n-06) received from the upper SDAP-layer device (2 n-07). Inaddition, a UDC header may be generated and attached by calculating thechecksum field and setting whether to apply the UDC (2 n-10). Inaddition, encryption may be performed on the UDC header and thecompressed UDC block, and a PDCP header 2 n-20 may be generated,configured, joined, and then forwarded to a lower layer to process datain RLC-layer devices and MAC-layer devices.

The procedure described in connection with FIG. 2N may be characterizedby applying a user data compression (UDC) procedure to the SDAP header.However, if the user data compression procedure is applied to the SDAPheader as in the above procedure, the SDAP header is encrypted becausethe encryption procedure is applied to the compressed UDC block.Therefore, it is impossible to obtain the advantages of the base-stationimplementation illustrated in FIG. 2K and the processing gains of thebase station and terminal described in connection with FIGS. 2L and 2M.Accordingly, an embodiment of the disclosure proposes a procedure thatdoes not apply a user data compression (UDC) procedure to the SDAPheader in order to obtain the advantages of the base-stationimplementation illustrated in FIG. 2K and described above and theprocessing gains of the base station and terminal illustrated in FIGS.2L and 2M.

FIG. 2O is a view for proposing and explaining a method of generating anSDAP header for data received from an upper layer without applying auser data compression (UDC) procedure to the SDAP header in a PDCP-layerdevice, according to an embodiment of the disclosure.

In FIG. 2O, when the SDAP-layer device is configured to use theSDAP-layer device function by using RRC messages such as 2 e-10 or 2e-40 or 2 e-75 in FIG. 2E, or when configured to use the SDAP header,and when user data compression (uplink data compression, UDC) isconfigured, when receiving data from the upper layer, the SDAP-layerdevice SDAP header may generate and configure the SDAP header as 2 o-05and transfer the same to the PDCP-layer device. The PDCP-layer devicemay perform user data compression on the rest of the data except theSDAP header in the PDCP SDU (SDAP header and IP packet, 2 o-06) receivedfrom the upper SDAP-layer device (2 o-07). In addition, a UDC header maybe generated and attached by calculating the checksum field and settingwhether to apply the UDC (2 o-10). If integrity protection isconfigured, integrity protection is applied to the UDC header and to thecompressed UDC block before performing the integrity protectionencryption procedure, and then encryption of the UDC block is performedin order to perform encryption on the UDC header and the compressed UDCblock. In addition, encryption may be separately performed in the UDCheader (2 o-15, 2 o-20). If encryption is performed only once, the SDAPheader is removed in the middle, encryption is performed on the UDCheader and the UDC block at once, the unencrypted SDAP header isinserted between the UDC header and the UDC block, data is configured,the PDCP header is generated and configured (2 o-20), bonded, andtransferred to the lower layer to perform data processing in theRLC-layer device and the MAC-layer device. As described above, ifencryption is applied to the UDC header even if the user datacompression header is not applied to the SDAP header, the user datacompression procedure in the terminal and base-station implementationbecome complicated, the procedure may needlessly be performed twice whenperforming encryption and decryption, and even if it is performed once,data processing may be complicated. Therefore, an embodiment of thedisclosure proposes a method of not performing encryption on the UDCheader. However, even if data processing is complicated, as describedabove, if the UDC header and data (UDC block) are encrypted separately,the risk of hacking can be effectively reduced and security can beincreased. Therefore, this can be an embodiment for enhancing securityin the disclosure.

The procedure illustrated in FIG. 2O may be characterized by notapplying a user data compression (UDC) procedure to the SDAP header.Therefore, it is impossible to obtain the advantages of the base-stationimplementation illustrated in FIG. 2K and the processing gains of thebase station and terminal illustrated in FIGS. 2L and 2M. However, evenif the user data compression header is not applied to the SDAP header,if encryption is applied to the UDC header, the user data compressionprocedure is complicated in the terminal and base-stationimplementation, and when performing encryption and decryption, it may beunnecessary to perform the same twice, and even if performed once, dataprocessing may be complicated. Therefore, an embodiment of thedisclosure proposes a method of not performing encryption on the UDCheader.

FIG. 2P is a view for proposing and explaining a method of generating anSDAP header for data received from an upper layer in a PDCP-layerdevice, not applying encryption to a UDC header, and not applying a userdata compression (UDC) procedure to the SDAP header in a PDCP-layerdevice, according to an embodiment of the disclosure.

In FIG. 2P, when the SDAP-layer device is configured to use theSDAP-layer device function by using RRC messages such as 2 e-10 or 2e-40 or 2 e-75 in FIG. 2E, or when configured to use the SDAP header,and when user data compression (uplink data compression, UDC) isconfigured, when receiving data from the upper layer, the SDAP-layerdevice may generate and configure the SDAP header as indicated by 2p-05, and may transfer the same to the PDCP-layer device. The PDCP-layerdevice may perform user data compression on the rest of the data exceptthe SDAP header in the PDCP SDU (SDAP header and IP packet, 2 p-06)received from the upper SDAP-layer device (2 p-07). In addition, ifintegrity protection is configured, integrity protection may be appliedto the UDC block compressed by the user data compression beforeperforming the encryption procedure. That is, integrity protection isnot applied to the UDC header or to the SDAP header. In addition,encryption may be applied to the UDC block compressed by the user datacompression (2 p-10). In addition, a UDC header may be generated andattached by calculating the checksum field and configuring whether toapply UDC (2 p-15, 2 p-20). In addition, the PDCP header may begenerated, configured, joined, and then transmitted to a lower layer toprocess data in the RLC-layer device and the MAC-layer device. Assuggested above, if the user data compression header is not applied tothe SDAP header and encryption is not applied to the UDC header, theuser data compression procedure and the encryption and decryptionprocedures are simplified in the terminal and base-stationimplementation, and complicated procedures are eliminated. Thissimplifies processing procedures of the implementation and reduces theprocessing burden thereof.

The procedure illustrated in FIG. 2P may be characterized in that theuser data compression (UDC) procedure is not applied to the SDAP headerand in that encryption is not performed on the UDC header. In addition,the procedure may be characterized in that encryption is not performedwithout applying integrity protection to the UDC header or to the SDAPheader. Therefore, it is possible to obtain the advantages of thebase-station implementation illustrated in FIG. 2K and the processinggains of the base station and terminal illustrated in FIGS. 2L and 2M.In addition, if encryption is not performed on the UDC header in theabove procedure, the validity of the UDC buffer contents can beconfirmed by first reading and calculating the checksum field of the UDCheader before performing decryption at the receiving end. Therefore, ifa checksum failure occurs, the amount of data to be processed can bereduced because the corresponding data can be immediately discarded anda checksum failure processing procedure can be performed withoutperforming a decoding procedure.

FIG. 2Q is a view illustrating a processing gain that can be obtained ina base station and a terminal implementation in an SDAP/PDCP-layerdevice or a bearer or a logical channel in which UDC is configured whenapplying an unencrypted SDAP header without user data compression andapplying an unencrypted UDC header according to an embodiment of thedisclosure.

In FIG. 2Q, when implementing a terminal and a base station, anSDAP-layer device and a PDCP-layer device may be integrated andimplemented as a single-layer device (2 q-01). Since the SDAP-layerdevice is logically the upper-layer device of the PDCP-layer device,when receiving data (2 q-05) from the upper application layer, in thecase in which the SDAP-layer device is configured to use the SDAP-layerdevice function or an SDAP header by an RRC message such as 2 e-10 or 2e-40 or 2 e-75 in FIG. 2E, when receiving data from the upper layer, theSDAP header should be generated and configured as 2 j-05 in FIG. 2J.However, in the implementation of the terminal and the base station, theciphering procedure can be implemented by applying a hardware (HW)accelerator because it is a highly complex operation. HW acceleratorshave high processing gains in repetitive and continuous procedures.However, if a process of configuring the SDAP header, performing theencryption procedure on the data portion excluding the SDAP header,generating the PDCP header, and attaching the same to the SDAP header isperformed whenever the SDAP-layer device receives data from theupper-layer device, it may interrupt the HW accelerator due to theprocedure of generating the SDAP header before performing encryption.

Therefore, the embodiment of the disclosure proposes a method forimplementing a single-layer device by integrating the SDAP-layer deviceand the PDCP-layer device in an implementation with an unencrypted SDAPheader in the case in which the ROHC is configured. That is, when datais received from the upper application layer, user data compression(UDC) is applied to compress the data of the upper layer to generate acompressed UDC block each time data is received, (2 q-05), an encryptionprocedure may be continuously and repeatedly performed, and the PDCPheader, the UDC header and the SDAP header (2 q-15) may be generated atthe same time, joined to the encrypted data, and transmitted to thelower layer. Generation of the PDCP header, the UDC header, and the SDAPheader may be performed in parallel with the encryption procedure. Whengenerating the headers in parallel, the SDAP header, PDCP header, UDCheader, RLC header and MAC header are generated together, and theheaders may be joined at the beginning of the data processing to thusprepare for transmission (MAC PDU configuration may be prepared). Inaddition, the receiving end may read all of the SDAP header, PDCPheader, UDC header, RLC header and MAC header at one time, identify allof the information corresponding to each layer, and process the data inthe reverse order of data processing at the transmitting end. Therefore,the HW accelerator can be continuously and repeatedly applied, and thereis no interruption such as SDAP header generation in the middle, therebyincreasing the efficiency of data processing. The HW accelerator canalso be applied to the user data compression procedure. In addition, ifintegrity protection is configured, integrity protection may berepeatedly performed by applying a hardware accelerator as described forthe encryption procedure before performing the encryption procedure.That is, integrity protection can be applied and encryption can beperformed.

As for the receiving PDCP-layer device, as in 2 q-01, a method ofintegrating the SDAP-layer device and the PDCP-layer device into asingle-layer device to implement a single-layer device can be applied inthe case in which the ROHC is configured. That is, when data is receivedfrom a lower layer (RLC layer), when the SDAP-layer device function isconfigured to be used by an RRC message such as 2 e-10 or 2 e-40 or 2e-75 in FIG. 2e , or when the SDAP header is configured to be used, thePDCP header, the UDC header, and SDAP header may be read and removed atonce, a deciphering procedure may be repeatedly applied to data, and auser data decompression procedure may be performed. In addition, ifencryption is not performed on the UDC header in the above procedure,the validity of the UDC buffer contents may be confirmed by firstreading and calculating the checksum field of the UDC header beforeperforming decryption at the receiving end. Therefore, if a checksumfailure occurs, the amount of data to be processed can be reducedbecause the corresponding data can be immediately discarded and achecksum failure processing procedure can be performed withoutperforming a decoding procedure. In addition, if integrity protection isconfigured, integrity verification can be repeatedly performed byapplying a hardware accelerator as described for the decryptionprocedure after performing the decryption procedure. That is, decryptioncan be performed and integrity verification can be performed.

FIG. 2R is a view illustrating the operations of a transmittingSDAP/PDCP-layer device and a receiving SDAP/PDCP-layer device in theSDAP/PDCP-layer device or the bearer or logical channel in which the UDCis configured when applying unencrypted SDAP header without user datacompression and with unencrypted UDC header, according to an embodimentof the disclosure.

In FIG. 2R, when implementing a terminal and a base station, anSDAP-layer device and a PDCP-layer device may be integrated andimplemented as a single-layer device (2 r-01). In an embodiment of thedisclosure, a method for integrating SDAP-layer devices and PDCP-layerdevices into a single-layer device by way of implementation with anon-encrypted SDAP header when UDC is configured is proposed. That is,when receiving data from the upper application layer (2 r-05), thetransmitting SDAP/PDCP-layer device may apply user data compression(UDC) whenever data is received to compress the data of the upper layerto generate a compressed UDC block (2 r-10) and continuously andrepeatedly perform the encryption procedures (2 r-15), and the PDCPheader, UDC header and SDAP header (2 r-20) can be generated at the sametime to thus be joined to the encrypted data and transmitted to a lowerlayer. Generation of the PDCP header, the UDC header, and the SDAPheader may be performed in parallel with the encryption procedure. Whengenerating the headers in parallel, the SDAP header, PDCP header, UDCheader, RLC header and MAC header can be generated together, and headerscan be joined at the beginning of data processing to prepare fortransmission (MAC PDU configuration can be prepared). In addition, thereceiving end may separate the SDAP header, PDCP header, UDC header, RLCheader, and MAC header from data at one time, read all the informationcorresponding to each layer, and process the data in the reverse orderof data processing at the transmitting end. Therefore, the HWaccelerator can be continuously and repeatedly applied, and there is nointerruption such as SDAP header generation in the middle, therebyincreasing the efficiency of data processing. The HW accelerator canalso be applied to the user data compression procedure.

Even in the receiving PDCP-layer device, the method of integrating theSDAP-layer device and the PDCP-layer device into a single-layer devicecan be applied when the UDC is configured. That is, when data isreceived from the lower layer (RLC layer) (2 r-25), the SDAP-layerdevice function is configured to use the SDAP-layer device function byan RRC message such as 2 e-10, 2 e-40, or 2 e-75 in FIG. 2E or isconfigured to use the SDAP header, and the receiving SDAP/PDCP-layerdevice may read and remove the PDCP header, the UDC header, and the SDAPheader all at once (2 r-30), repeatedly apply a decoding procedure tothe data (2 r-35), perform a user data decompression procedure, andtransmit the result thereof to the upper layer (2 r-40).

In the above-described embodiment of the disclosure, there is proposed amethod in which the SDAP layer and the PDCP layer are implemented in anintegrated manner, the data processing of the PDCP-layer device isperformed in order to remove the interference of the HW accelerator dueto the generation of the SDAP header for each piece of received data,and when generating the PDCP header, the UDC header or SDAP header isused, and the advantages of reducing the number of unnecessary memoryaccesses caused by generating the SDAP header in advance and increasingthe efficiency of the HW accelerator have been explained. In addition,the proposed method can efficiently perform terminal data processing onthe receiving side of the terminal in the same manner.

In the embodiment of the disclosure, the implementation complexity andproblems that may occur due to the generation and encryption of SDAPheaders (ciphering) and uplink data compression (UDC) truncation aredescribed, and a method for solving the problems is proposed.

In the above, whether to use the SDAP header for each bearer may beconfigured as an RRC message by the base station, as illustrated in FIG.2E, and whether the UDC for each bearer is applied may also beconfigured by the base station as an RRC message, as described above.

In the next embodiment of the disclosure, it is proposed that the SDAPheader and the UDC cannot be simultaneously used for one bearer when thebase station sets whether to use the SDAP header for each bearer andwhether to apply the UDC as an RRC message (the SDAP header cannot beconfigured for a DRB configured with UDC, or both SDAP header and UDCcannot be configured for a DRB, or either an SDAP header or UDC can beconfigured for a DRB, not both). That is, it is possible to prohibit thebase station from simultaneously configuring the use of the SDAP headerand the UDC application for one bearer in an RRC message. As describedabove, when the UDC procedure is performed on the UDC-configured bearer,the UDC procedure is complicated, and implementation complexity isfurther increased due to generation and non-encryption of the SDAPheader. The UDC is applied to the uplink data, and when the SDAP headeris configured for the uplink data, this corresponds to the case whereremapping between the bearer and the flow is configured. In this case,it might not be appropriate to use UDC. This is because it is veryinefficient to perform re-mapping between bearers and flows to thebearer to which the UDC is applied because the UDC procedure needs thetransmitting end and receiving end to be synchronized for datacompression. Therefore, if the use of the SDAP header and the setting ofthe UDC are not simultaneously set for one bearer in order to deal withthe above-described complexity, the complex problems described above donot occur. Therefore, in another embodiment of the disclosure, the basestation does not allow the UE to simultaneously configure the use of theSDAP header and the UDC for one bearer.

In the above, when the base station does not simultaneously configurethe use of the SDAP header and the UDC for a single bearer to theterminal, the UDC header can be encrypted for enhanced security. Thatis, when receiving upper-layer data, after data compression is performedby a UDC procedure, a UDC header may be generated, ciphering may beperformed on the UDC header and the compressed UDC data block, and aPDCP header may be generated in front of the encrypted UDC header andthe UDC data block to be concatenated and transferred to a lower layer.

As another method, when the base station does not simultaneouslyconfigure the use of the SDAP header and the UDC for a single bearer,the base station can quickly check the checksum field of the UDC headerand quickly determine whether to discard the UDC data in order to reducethe number of decoding procedures. That is, the UDC header might not beencrypted. That is, when receiving the upper-layer data, datacompression may be performed by a UDC procedure, encryption may beperformed on the compressed data block, and a UDC header and PDCP headermay be generated to be concatenated in front of the encrypted UDC datablock and transferred to a lower layer. Therefore, the receivingPDCP-layer device may check the UDC header before performing decryption,check the validity of the UDC with the checksum field, and if it is notvalid, discard the received data immediately without performingdecryption. Decryption may be performed only on data that is verified asthe checksum field, and a user data decompression procedure may beperformed.

In addition, the integrity verification protection procedure may alsocause a complicated implementation problem when the integrityverification protection procedure is configured for one bearer with SDAPheader use or UDC application. Therefore, it is not possible to allowSDAP header usage and integrity verification protection to besimultaneously set in one bearer. In addition, it might not be permittedto simultaneously configure the integrity verification and UDCapplication for one bearer.

FIG. 2S is a view showing the configuration of a terminal according toan embodiment of the disclosure.

Referring to FIG. 2S, the terminal includes a radio-frequency (RF)processor 2 s-10, a baseband processor 2 s-20, a storage unit 2 s-30,and a controller 2 s-40. The controller 2 s-40 may further include amultiple-connection processor 2 s-42.

The RF processor 2 s-10 performs a function for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 2 s-10up-converts a baseband signal provided from the baseband processor 2s-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 2 s-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital-to-analog converter (DAC), ananalog-to-digital converter (ADC), etc. In FIG. 1H, although only oneantenna is illustrated, the terminal may have multiple antennas. Also,the RF processor 2 s-10 may include a plurality of RF chains.Furthermore, the RF processor 2 s-10 may perform beamforming. For thebeamforming, the RF processor 2 s-10 may adjust the phase and magnitudeof each of signals transmitted and received through multiple antennas orantenna elements. In addition, the RF processor may perform MIMO, andmay receive multiple layers when performing MIMO operations. The RFprocessor 2 s-10 may perform reception beam sweeping by appropriatelyconfiguring a plurality of antennas or antenna elements under thecontrol of the controller, or may adjust the direction and beam width ofthe reception beam so that the reception beam is coordinated with thetransmission beam.

The baseband processor 2 s-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical-layerstandard of a system. For example, during data transmission, thebaseband processor 2 s-20 generates complex symbols by encoding andmodulating a transmission bit stream. In addition, upon receiving data,the baseband processor 2 s-20 restores the received bit stream throughdemodulation and decoding of the baseband signal provided from the RFprocessor 2 s-10. For example, in the case of conforming to anorthogonal frequency-division multiplexing (OFDM) method, whentransmitting data, the baseband processor 2 s-20 encodes and modulates atransmission bit stream to generate complex symbols, maps the complexsymbols to subcarriers, and then configures OFDM symbols via an inversefast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. In addition, when receiving data, the baseband processor 2s-20 divides the baseband signal provided from the RF processor 2 s-10into units of OFDM symbols, restores signals mapped to subcarriers via afast Fourier transform (FFT) operation, and then restores a received bitstream via demodulation and decoding.

The baseband processor 2 s-20 and the RF processor 2 s-10 transmit andreceive signals as described above. Accordingly, each of the basebandprocessor 2 s-20 and the RF processor 2 s-10 may be referred to as atransmitter, a receiver, a transceiver, or a communicator. Furthermore,at least one of the baseband processor 2 s-20 and the RF processor 2s-10 may include a plurality of communication modules to support aplurality of different radio access technologies. In addition, at leastone of the baseband processor 2 s-20 and the RF processor 2 s-10 mayinclude different communication modules to process signals in differentfrequency bands. For example, the different radio access technologiesmay include an LTE network, an NR network, and the like. In addition,the different frequency bands may include a super-high-frequency (SHF)(e.g., 2.5 GHz, 5 GHz) band and a millimeter-wave (e.g., 60 GHz) band.

The storage unit 2 s-30 stores data such as a basic program, anapplication, and configuration information for the operation of theterminal. The storage unit 2 s-30 provides stored data in response to arequest from the controller 2 s-40.

The controller 2 s-40 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 2 s-40 transmits and receives signals through the basebandprocessor 2 s-20 and the RF processor 2 s-10. In addition, thecontroller 2 s-40 records and reads data in the storage unit 2 s-30. Tothis end, the controller 2 s-40 may include at least one processor. Forexample, the controller 2 s-40 may include a communication processor(CP) that performs control for communication and an applicationprocessor (AP) that controls an upper layer such as an application.

FIG. 2T is a view illustrating the configuration of a base stationaccording to an embodiment of the disclosure.

As illustrated in FIG. 2T, the base station includes an RF processor 2t-10, a baseband processor 2 t-20, a backhaul communicator 2 t-30, astorage unit 2 t-40, and a controller 2 t-50. The controller 2 t-50 mayfurther include a multiple-connection processor 2 t-52.

The RF processor 2 t-10 performs functions for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 2 t-10up-converts a baseband signal provided from the baseband processor 1i-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 2 t-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, an ADC, etc. In FIG. 2T, although only oneantenna is illustrated, the first connection node may have multipleantennas. Also, the RF processor 2 t-10 may include a plurality of RFchains. Furthermore, the RF processor 2 t-10 may perform beamforming.For the beamforming, the RF processor 2 t-10 may adjust the phase andmagnitude of each of signals transmitted and received through multipleantennas or antenna elements. The RF processor may perform down-MIMOoperations by transmitting one or more layers.

The baseband processor 2 t-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical-layerstandard of the first wireless access technology. For example, duringdata transmission, the baseband processor 2 t-20 generates complexsymbols by encoding and modulating a transmission bit stream. Inaddition, upon receiving data, the baseband processor 2 t-20 restoresthe received bit stream through demodulation and decoding of thebaseband signal provided from the RF processor 2 t-10. For example, inthe case of conforming to the OFDM method, when transmitting data, thebaseband processor 2 t-20 encodes and modulates a transmission bitstream to generate complex symbols, maps the complex symbols tosubcarriers, and then configures OFDM symbols via IFFT operation and CPinsertion. In addition, when receiving data, the baseband processor 2t-20 divides the baseband signal provided from the RF processor 2 t-10into units of OFDM symbols, restores signals mapped to subcarriers viathe FFT operation, and then restores a received bit stream viademodulation and decoding. The baseband processor 2 t-20 and the RFprocessor 2 t-10 transmit and receive signals as described above.Accordingly, each of the baseband processor 2 t-20 and the RF processor2 t-10 may be referred to as a transmitter, a receiver, a transceiver,or a communicator.

The backhaul communicator 2 t-30 provides an interface for performingcommunication with other nodes in a network.

The storage unit 2 t-40 stores data such as a basic program, anapplication, and configuration information for the operation of theterminal. In particular, the storage unit 2 t-40 may store informationon bearers allocated to the connected terminal, measurement resultsreported from the connected terminal, and the like. In addition, thestorage unit 2 t-40 may store information serving as a criterion fordetermining whether to provide or interrupt multiple connections to theterminal. Then, the storage unit 2 t-40 provides stored data in responseto a request from the controller 2 t-50.

The controller 2 t-50 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 2 t-50 transmits and receives signals through the basebandprocessor 2 t-20 and the RF processor 2 t-10 or through the backhaulcommunicator 2 t-30. In addition, the controller 2 t-50 records andreads data in the storage unit 2 t-40. To this end, the controller 2t-50 may include at least one processor.

Third Embodiment

FIG. 3A is a view illustrating the structure of an LTE system accordingto an embodiment of the disclosure.

Referring to FIG. 3A, as illustrated, the wireless access network of theLTE system is composed of next-generation base stations (evolved node B,hereinafter “ENB”, “Node B” or “base station”) 3 a-05, 3 a-10, 3 a-15,and 3 a-20, a mobility management entity (MME) 3 a-25, and a servinggateway (S-GW) 3 a-30. A user equipment (hereinafter, UE or terminal) 3a-35 is connected to an external network through the ENB 3 a-05, 3 a-10,3 a-15, and 3 a-20 and the S-GW 3 a-30.

In FIG. 3A, the ENBs 3 a-05, 3 a-10, 3 a-15, and 3 a-20 correspond tothe existing node B of a UMTS system. The ENB 3 a-05 is connected to theUE 3 a-35 by a wireless channel and performs a more complicated rolethan the existing Node B. In the LTE system, since all user trafficincluding real-time services such as Voice over IP (VoIP), carried overthe Internet protocol, are served through a shared channel, a device isrequired to perform scheduling by collecting status information, such asbuffer status, available transmission power status, and channel statusof UEs, and the ENBs 3 a-05, 3 a-10, 3 a-15, and 3 a-20 are responsibletherefor. One ENB usually controls multiple cells. For example, in orderto realize a transmission rate of 100 Mbps, the LTE system usesorthogonal frequency-division multiplexing (OFDM) in, for example, a 20MHz bandwidth, as a radio access technology. In addition, an adaptivemodulation and coding (hereinafter, referred to as AMC) method isapplied to determine the modulation scheme and the channel-coding rateaccording to the state of the channel used by a terminal. The S-GW 3a-30 is a device that provides a data bearer and creates or removes adata bearer under the control of the MME 3 a-25. The MME 2 a-25 is adevice that is responsible for various control functions as well asmobility management functions for the terminals 3 a-35, and is connectedto multiple base stations 3 a-05, 3 a-10, 3 a-15, and 3 a-20.

FIG. 3B is a view illustrating a radio protocol structure in an LTEsystem according to an embodiment of the disclosure.

Referring to FIG. 3B, the wireless protocol of the LTE system iscomposed of a packet data convergence protocol (PDCP) 3 b-05 and 3 b-40,radio link control (RLC) 3 b-10 and 3 b-35, and medium access control(MAC) 3 b-15 and 3 b-30, in a terminal and ENB. The packet dataconvergence protocols (PDCPs) 3 b-05 and 3 b-40 are responsible for IPheader compression/decompression. The main functions of the PDCP aresummarized as follows.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper-layer PDUs at PDCP        re-establishment procedure for RLC AM    -   For split bearers in DC (only support for RLC AM): PDCP PDU        routing for transmission and PDCP PDU reordering for reception    -   Duplicate detection of lower-layer SDUs at PDCP re-establishment        procedure for RLC AM    -   Retransmission of PDCP SDUs at handover and, for split bearers        in DC, of PDCP PDUs at PDCP data recovery procedure, for RLC AM    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

The radio link control (hereinafter, referred to as RLC) 3 b-10 and 3b-35 reconfigures the PDCP packet data unit (PDU) to an appropriate sizeto perform an ARQ operation. The main functions of RLC are summarized asfollows.

-   -   Transfer of upper-layer PDUs    -   Error correction through ARQ (only for AM data transfer)    -   Concatenation, segmentation and reassembly of RLC SDUs (only for        UM and AM data transfer)    -   Re-segmentation of RLC data PDUs (only for AM data transfer)    -   Reordering of RLC data PDUs (only for UM and AM data transfer)    -   Duplicate detection (only for UM and AM data transfer)    -   Protocol error detection (only for AM data transfer)    -   RLC SDU discard (only for UM and AM data transfer)    -   RLC re-establishment

The MACs 3 b-15 and 3 b-30 are connected to various RLC-layer devicesconfigured in a terminal or a base station, and perform operations ofmultiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MACPDUs. The main functions of MAC are summarized as follows.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TB)        delivered to/from the physical layer on transport channels    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification function    -   Transport format selection function    -   Padding function

The physical layers 3 b-20 and 3 b-25 channel-code and modulate theupper-layer data, convert the same into an OFDM symbol and transmit thesame to a radio channel, or demodulate and decode an OFDM symbolreceived through the radio channel and transmit the same to the upperlayer.

FIG. 3C is a view showing the structure of a next-generation mobilecommunication system according to an embodiment of the disclosure.

Referring to FIG. 3C, the radio access network of the next-generationmobile communication system includes a next-generation base station (newradio Node B, hereinafter NR gNB or NR base station) 3 c-10 and a newradio core network (NR CN) 3 c-05. The user terminal (new radio userequipment, hereinafter NR UE or terminal) 3 c-15 accesses an externalnetwork through the NR gNB 3 c-10 and the NR CN 3 c-05.

In FIG. 3C, the NR gNB 3 c-10 corresponds to an evolved node B (eNB) ofan existing LTE system. The NR gNB 3 c-10 is connected to the NR UE 3c-15 through a wireless channel, and can provide service superior to theexisting Node B. In the next-generation mobile communication system,since all user traffic is served through a shared channel, a device isrequired to collect and schedule status information such as bufferstatus of UEs, available transmission power status, and channel status,and the NR NB 3 c-10 is responsible therefor. One NR gNB 3 c-10 usuallycontrols multiple cells. In order to implement ultra-high-speed datatransmission compared to the current LTE, more than the existing maximumbandwidth may be provided, and an orthogonal frequency-divisionmultiplexing (OFDM) radio access technology may be additionally combinedwith the beamforming technology. In addition, an adaptive modulation andcoding (hereinafter, referred to as “AMC”) method is applied todetermine the modulation scheme and the channel-coding rate according tothe state of the channel used by a terminal. The NR CN 3 c-05 performsfunctions such as mobility support, bearer setup, and QoS configuration.The NR CN 3 c-05 is a device that is responsible for various controlfunctions as well as mobility management functions for a terminal 3c-15, and is connected to multiple base stations. In addition, thenext-generation mobile communication system can be linked with theexisting LTE system, and the NR CN 3 c-05 is connected to the MME 3 c-25through a network interface. The MME 3 c-25 is connected to the eNB 3c-30, which is the existing base station.

FIG. 3D is a view for explaining new functions for handling QoS in an NRsystem according to an embodiment of the disclosure.

In the NR system, a service requiring different quality of service(QoS), that is, a user traffic transmission path, should be configuredaccording to QoS requirements, or IP flow for each service should becontrolled. The NR core network may establish a plurality of packet dataunit (PDU) sessions, and each PDU session may include a plurality of IPflows. The NR gNB can map a plurality of QoS flows to a plurality ofdata radio bearers (DRBs) and simultaneously configure the same. Thatis, for the downlink, a plurality of QoS flows 3 d-01, 3 d-02, 3 d-03can be mapped to the same DRB or to different DRBs 3 d-10, 3 d-15, 3d-20. In order to do this, it is necessary to mark the QoS flow ID inthe downlink packet. Alternatively, DRB mapping can be explicitlyconfigured through an RRC control message. Since the above functions arenot available in the existing LTE PDCP protocol, a new protocol (servicedata adaptation protocol (SDAP)) 3 d-05, 3 d-40, 3 d-50, 3 d-85 has beenintroduced. In addition, the above indication allows the terminal toimplement reflective QoS for uplink. “Reflective QoS” means a method ofmapping to allow a terminal to perform uplink transmission through a DRBthrough which a downlink packet having a specific flow ID transmitted bythe gNB is transmitted, and to indicate this, 1 or 2 reflective QoSindicator (RQI) bits may be included in the SDAP header. Explicitlydisplaying the QoS flow ID in the downlink packet as described above isa simple method in which the access stratum (AS) of the terminalprovides the information to the NAS of the terminal. The method ofmapping IP flows to DRBs in the downlink may be performed in thefollowing two steps.

-   1. NAS level mapping: IP flow→QoS flow-   2. AS level mapping: QoS flow→DRB

In the downlink reception, the presence or absence of QoS flow mappinginformation and reflective QoS operation for each received DRB 3 d-25, 3d-30, 3 d-35 can be identified for each received DRB 3 d-25, 3 d-30, 3d-35, and the corresponding information can be transmitted to the NAS.That is, if the RQI bits are configured as 1 in the SDAP header of thereceived data packet, the terminal indicates that the AS and NAS-mappingrules have been updated, and thus the mapping rules can be updated andthe uplink packets can be transmitted accordingly. That is, two steps ofmapping can be used for the uplink as well. First, IP flows are mappedto QoS flows through NAS signaling, and QoS flows are mapped to DRBs 3d-55, 3 d-60, 3 d-65 defined in the AS. The terminal may indicate theQoS flow ID in the uplink packet, or may transmit the packet as it iswithout displaying the QoS flow ID. The function is performed in theSDAP of the terminal. When the QoS flow ID is indicated in the uplinkpacket, the base station may display and transmit the QoS flow IDwithout an uplink traffic flow template (TFT) to the packet thatdelivers the information to the NG-U.

FIGS. 3EA and 3EB are views illustrating protocol stacks including SDAPsin the NR according to an embodiment of the disclosure.

In order to deal with the new QoS function of the NR system, thefollowing information must be transmitted through the wirelessinterface.

Downlink: QOS flow ID+Reflective QOS processing required indicator

Uplink: QOS flow ID

In the NR, an interface for transmitting the above new information to Uuis required, and a new protocol responsible for the function is definedon the PDCP (3 e-10) layer. The SDAP 3 e-05 is not a DRB-based protocol,but a packet is transmitted according to the established DRB 3 e-30mapping rule. That is, when IP traffic occurs, the IP flow is mapped tothe QoS flow ID in the SDAP 3 e-05 and then the QoS flow ID is mapped tothe DRB. Here, the IP traffic is composed of an IP header and a payload,and SDAP headers 3 e-35, 3 e-40, 3 e-45 can be located in front of theIP packet. In PDCP 3 e-10, IP header compression is performed and PDCPheaders 3 e-50, 3 e-55, 3 e-60 are added. In the RLC 3 e-15 and MAC 3e-20, each RLC header 3 e-65, 3 e-70, 3 e-75, 3 e-80 and a MACsub-header 3 e-65 are sequentially added. After adding the MAC headers,the MAC PDU is delivered to the PHY.

When the gNB determines to apply the reflective mechanism (indicates theterminal to send an uplink packet to the same DRB where the QoS flow IDincluded in the downlink packet is delivered) to the UE, the QoS flow IDand reflective QoS indicator are delivered to the SDAP 3 e-05 layer ofthe downlink packet. The SDAP header may have a length of 1 byte, andmay be composed of a QoS flow ID (7 bits) and an RQI (1 bits).Alternatively, the SDAP header may be composed of QoS flow ID (6 bits)and an RQI (2 bits), in which case the RQI indicator indicates thereflective QoS of each of the AS and NAS. In the following, it isassumed that one RQI bit is configured.

In performing the above process, when the gNB delivers the QoS flow IDto all data packets, the terminal continuously performs an operation ofupdating the mapping rule through the received QoS flow ID. That is,when the RQI bit is set to 1, the terminal updates the NAS-mapping ruleand the AS-mapping rule and transmits an uplink data packet according tothe corresponding rule on the assumption that both the NAS- andAS-mapping rules have been updated. Basically, the NAS reflective QoS istriggered when the mapping rule between IP flow and QoS flow in the NRcore network is updated, and the AS reflective QoS is triggered when themapping rule between QoS flow and DRB in the wireless base station isupdated.

However, considering the signaling standard between the base station andthe core network, the core network configures and transmits an RQI bitindicating the N3 header of the data packet transmitted to the basestation when the NAS-mapping rule is updated. In the above, the N3header is an interface between the core network and the base station. Ifthe RQI bit of the N3 header received from the core network isconfigured to 1, the base station configures the RQI bit of the SDAPheader to 1 and transmits the same to the terminal. Alternatively, evenif the RQI bit of the N3 header is 0, when the AS-mapping rule ischanged, the base station configures the RQI bit of the SDAP header to 1and transmits the same to the terminal. However, if the above operationis performed, since the terminal side should keep storing the mappinginformation table (TFT table) for NAS mapping and AS mapping, the amountof information to be stored by the terminal may increase, and if notproperly managed, confusion due to duplicate mapping may occur. To solvethis, a timer is activated in the terminal and the NR core network atthe moment that the NAS reflective QoS rule is applied, and if the datapacket to which the rule is applied is not received for a preset timer,the configured NAS reflective QoS mapping information is removed. Forreference, when a data packet to which the same QoS mapping rule isapplied is transmitted and received while the timer is running, thetimer is restarted.

In an embodiment of the disclosure, problems and issues due todifferences in the QoS flow and DRB mapping operation in an NR systemcompared to an LTE system will be identified and resolved. Basically,the LTE system has 1:1 mapping between the evolved packet system (EPS)and the DRB, and the established mapping is maintained until thecorresponding service is terminated. On the other hand, in the NRsystem, QoS flow and DRB mapping can be dynamically configured, so aspecific QoS flow can be mapped to a DRB different from the initiallyconfigured DRB. In addition, as described above, the base station canrecognize that a new QoS flow is transmitted through a specific DRB onlywhen the first packet of the new QoS flow transmitted by the terminal isreceived. However, when there is a lot of data of the QoS flow bufferedin the corresponding DRB, a delay occurs in recognizing that a new QoSflow has been transmitted. In an embodiment of the disclosure, asolution to the following two issues is proposed to solve this problem.

1. Suggestion of terminal operation to enable the scheduler of the basestation to quickly recognize the first packet of a new QoS flow receivedby a specific DRB.

2. Proposal to prevent infrequent QoS flow mapping update operation atthe receiving end by guaranteeing in-sequence delivery of the changedDRB and data packets from the previous DRB when re-mapping QoS accordingto DRB change.

FIG. 3F is a view for explaining problems and issues when a first packetof a new QoS flow in a specific DRB is received in a delayed manner,considered in an embodiment of the disclosure.

In phase 1, a terminal receives the configurations for DRBs via an RRCmessage of a base station. The configurations include detailed layer(MAC, RLC, PDCP) configuration information of DRBs, information aboutDRBs to which each QoS flow will be delivered, and information aboutwhich DRB is the default DRB. Viewing the transmitting end of theterminal, each of the QoS flows 3 f-05, 3 f-10, 3 f-15 is delivered tothe DRB initially set in the SDAP layer 3 g-20, that is, packet deliveryand transmission for an operation for data transmission are performed tolower layers of specific DRBs 3 f-25 and 3 f-30. In FIG. 3F, QoS flow #1and QoS flow #2 are configured as DRB 2, and QoS flow #1 is mapped toDRB 1, where DRB 1 is configured as default DRB.

In the NR, the mapping between the DRB and the QoS flow may be changedregardless of whether handover is performed, and the QoS flow may bechanged to a DRB different from the previous DRB due to the change inthe mapping rule. Alternatively, if the newly generated uplink packetdoes not satisfy the mapping rule set to RRC or the reflective QoSmapping rule, the packet of the corresponding QoS flow is transmittedthrough the default DRB. When the DRB mapping of a new uplink packet ora packet having a specific QoS flow is different, the UE delivers apacket corresponding to the QoS flow through the default DRB or thechanged DRB.

In phase 2, when QoS flows such as 3 f-35, 3 f-40, and 3 f-45 are mappedto a new DRB, in operation 3 f-50, the corresponding SDAP SDU isclassified in the SDAP layer, and the SDAP PDU is transmitted to thecorresponding DRB and to lower layers. This example shows the case whereQoS flow #2 is changed from DRB 2 3 f-60 to DRB 1 3 f-55, which is thedefault DRB. The change is performed after the 26th SDAP PDU of QoS flow#2 is delivered and before the 27th SDAP PDU is delivered. The previousSDAP PDUs will be delivered to DRB 2, and the corresponding SDAP PDUsare delivered to DRB 1 after the mapping rule is changed. Here, the SDAPPDU numbers are not actually existing numbers, but are written to aid inunderstanding. However, due to differences in packets stored in thetransmission buffer for each DRB, the actual order of delivery to thereceiving end may be different. That is, a new packet of DRB 2 (packet27 of QoS flow #2) may be received before packets of the previous DRB 1.

In Phase 3, the receiving end, and precisely the receiving end of thebase station, receives packets transmitted by the terminal, and theorder in which the packets are received depends on how much data is inthe buffer for each DRB (3 f-65). In this example, it can be seen thatout-of-sequence delivery occurs for packets of QoS flow #2, so thatreceived packets are received with ping-pong effect between differentDRBs. In this case, since it is interpreted that the new QoS flow iscontinuously mapped through the corresponding DRB, the receiver of thebase station performs an unintended QoS reflective operation. A methodfor solving this will be described in the following examples.

FIG. 3G is a view for explaining a method of preferentially processing acorresponding SDAP packet when a new QoS flow is received in thereceiving SDAP layer of the terminal according to Embodiment 3-1 of thedisclosure.

This embodiment deals with a method for solving a transmission timedelay that may occur when reception of the first packet of the new QoSflow delivered to the changed DRB is slow, that is, when other QoS flowpackets are already accumulated in the transmission buffer of the DRB.Basically, if a specific QoS flow is changed from a previous DRB toanother DRB, the changed DRB should be quickly identified at thereceiving end, and the scheduler of the base station should quicklyschedule and process the corresponding QoS flow. To this end, theembodiment deals with a method of delivering SDAP PDUs to be processedand delivered first.

In phase 1, the terminal receives configurations for DRBs through theRRC message of the base station. The configurations include detailedlayer (MAC, RLC, PDCP) configuration information of DRBs, informationabout the DRBs to which each QoS flow will be delivered, and informationabout which DRB is the default DRB. Viewing the transmitting end of theterminal, each of the QoS flows 3 g-05, 3 g-10, 3 g-15, 3 g-20 isdelivered to the DRB initially set in an SDAP layer 3 g-25, that is,packet delivery and transmission for an operation for data transmissionare performed in (?) lower layers of specific DRBs 3 g-30, 3 g-35, 3g-40. In FIG. 3G, it is assumed that QoS flow #1 is configured as DRB 3,that QoS flow #2 and QoS flow #5 are configured as DRB 2, and that QoSflow #3 is mapped to DRB 1, where DRB 1 is configured as a default DRB.

In phase 2, if the receiving end of the terminal accurately receives theSDAP SDU of the new downlink QoS flow from the base station in thereceiving SDAP layer of the terminal, that is, if QoS flow #4 waspreviously transmitted and received through DRB 2 (3 g-50) but a newdownlink packet corresponding to QoS flow #4 is received by DRB 1 (3g-45), the terminal updates the mapping rules between the QoS flow andthe DRB and then performs transmission/reception with the DRB 1 (3 g-45)for the subsequent QoS flow #4.

In phase 3, the transmitting end of the terminal needs to quicklydeliver the first packet (3 g-75) for the new QoS flow #4 to DRB 1 (3g-70) according to the mapping rule update of the QoS flow and the DRBdetermined in the previous operation. If a large number of packetscorresponding to different QoS flows are accumulated in the transmissionbuffer of DRB 1 (3 g-70), this operation is necessary because the updateof the new QoS flow #4 packet can be performed slowly and can be solvedby the following procedure.

1. The SDAP layer of the terminal indicates to the PDCP layer whetherexpedited delivery is required for the SDAP PDU (requires messagetransfer between SDAP and PDCP layers).

2. In the PDCP layer, the PDCP PDU including the packet indicated by theSDAP layer is delivered to the lower layer, and the corresponding PDCPPDU is delivered before other PDCP PDUs waiting in the buffer. To thisend, an indicator indicating expedited delivery may be included in thePDCP header. This serves as an instruction not to trigger the reorderingtimer at the receiving end, so the packet can be quickly delivered tothe upper layer of the receiving end.

3. In the RLC layer, an RLC PDU including a packet received from thePDCP is generated and positioned so that the packet can be deliveredbefore other RLC PDUs stored in the RLC buffer.

FIG. 3H is a view for explaining a method for guaranteeing in-sequencedelivery at a receiving end when a QoS flow is re-mapped according toEmbodiment 3-2 of the disclosure.

As illustrated in FIG. 3F, when the DRB of the new QoS flow is changed,out-of-sequence delivery occurs, so received packets can be receivedwith ping-pong effect between different DRBs. In this case, since thenew QoS flow is continuously mapped through the corresponding DRB, thereceiver of the base station performs an unintended QoS reflectiveoperation. In this embodiment, a method for solving this is proposed.

In phase 1, a terminal receives the configurations for DRBs through theRRC message of the base station. The configurations include detailedlayer (MAC, RLC, PDCP) configuration information of DRBs, informationabout DRBs to which each QoS flow will be delivered, and informationabout which DRB is the default DRB. Viewing the transmitting end of theterminal, each of the QoS flows 3 h-05, 3 h-10, 3 h-15 is delivered tothe DRB initially set in an SDAP layer 3 g-20; that is, packet deliveryand transmission for a data transmission operation are performed inlower layers of specific DRBs 3 h-25, 3 h-30. In FIG. 3H, QoS flow #1and QoS flow #2 are configured as DRB 2 (3 h-30), and QoS flow #1 ismapped to DRB 1 (3 h-25), where DRB 1 (3 h-25) is configured as defaultDRB.

In phase 2, when QoS flows 3 h-35, 3 h-40, and 3 h-45 are mapped to anew DRB, in operation 3 h-50, the SDAP SDU is classified in the SDAPlayer, and the SDAP PDU is delivered to the corresponding DRB and thelower layer. This example shows the case where QoS flow #2 is changedfrom DRB 2 (3 f-60) to DRB 1 (3 f-55), which is the default DRB. Thechange is performed after the 26th SDAP PDU of QoS flow #2 is deliveredand before the 27th SDAP PDU is delivered. The previous SDAP PDUs willbe delivered to DRB 2 (3 h-60), and the corresponding SDAP PDUs aredelivered to DRB 1 (3 h-55) after the mapping rule is changed.

Here, the SDAP PDU numbers are not actually existing numbers, but arewritten to aid in understanding. However, due to differences in packetsstored in the transmission buffer for each DRB, the actual order ofdelivery to the receiving end may be different. That is, a new packet(packet 27 of QoS flow #2) of DRB 2 (3 h-60) may be received beforepackets of the previous DRB 1 (3 h-55). This may be explained asre-mapping from the previous PDCP A of the corresponding QoS flow #2 tothe new PDCP B. In order to solve the above out-of-sequence deliveryproblem, the following procedure is proposed.

1. An RRC message that resets a specific QoS flow of a specific PDUsession from a previous DRB to a new DRB is received.

2. The SDAP entity to reconfigure QoS in the RRC of a terminal isindicated.

3. When the SDAP entity receives the first packet of the new QoS flowthrough the new DRB, it performs a filtering operation (that is, itdiscards the SDAP PDU of the corresponding QoS flow received through theprevious DRB).

Due to the above operation, the terminal performs packet transmission toguarantee in-sequence delivery. That is, filtering is applied to packets24, 25, and 26 of QoS flow #2, which is discarded from the buffer. Inphase 3, the receiving end, precisely the receiving end of the basestation, receives the packets delivered by the terminal. Due to theproposed operation, out-of-sequence delivery of the packets of QoS flow#2 does not occur anymore. That is, it can be seen that the receivedpacket is no longer received with ping-pong effect between differentDRBs. Instead, data stored in the transfer buffer of the previous DRBare lost and transferred through the retransmission operation.

FIG. 3I is a view illustrating a method for delivering a new QoS flowpacket when mapping of changes in QoS flow and DRB is performed, asproposed in an embodiment of the disclosure.

Here, the method proposed in the above embodiments 3-1 and 3-2 isapplied, and FIG. 3I illustrates the entire operation in which, when themapping of the QoS flow and the DRB is changed thereby, the first packetof the new QoS flow transmitted to the new DRB is first transmitted andthe corresponding QoS flow packets stored in the transmission buffer ofthe previous DRB are discarded, thereby guaranteeing in-sequencedelivery at the base-station receiving end.

After the terminal camps on the serving cell (3 i-05), the terminalconfigures RRC connection to the cell and transitions to the connectionmode (3 i-10). In operation 3 i-15, the terminal receives the RRCconnection reconfiguration message from the base station, and receivesconfiguration DRBs, default DRB indication, and mapping informationbetween QoS flow and DRB. As an example of the configuration, in FIG. 3,DRB 1, DRB 2, and DRB 3 are configured, DRB 1 is indicated as a defaultDRB, and QoS flow mappings corresponding to DRB 1 and DRB 2 may beconfigured. In operation 3 i-20, the terminal receives a downlink datapacket transmitted by the base station. Specifically, in the aboveoperation, the terminal receives the SDAP SDU via the preset DRB x anddecodes the SDAP header of the corresponding packet to check the QoSflow ID. In operation 3 i-25, the terminal transmits the PDCP of the DRBx to the lower layer without any special action because thecorresponding SDAP SDU is received through the preset DRB x. That is, aseparate expedited delivery operation is not configured. The aboveexpedited delivery operation is illustrated in FIG. 3G, and is a methodin which a terminal informs a lower layer of an SDAP SDU requiringexpedited delivery.

If the SDAP SDU of the new QoS flow is received through the specific DRBin the SDAP of the UE in operation 3 i-30, it is necessary to quicklyprocess the QoS flows indicated by the first packet. That is, inoperation 3 i-35, the SDAP layer of the terminal transmits thecorresponding SDAP PDU to the PDCP of the default DRB (or modified DRB)including an expedited (ED) indicator. Here, the ED indicator may beincluded as 1 bit in the PDCP header. Then, the PDCP layer allocates aPDCP sequence number (SN) to the corresponding PDCP SDU, and if the EDindicator is included, the PDCP PDU is transmitted to the lower layerwith high priority. In addition, in the RLC layer, the RLC SN isallocated to the corresponding RLC SDU, and if the ED indicator isincluded, the RLC PDU is transmitted to the lower layer with highpriority.

In operation 3 i-40, the terminal also receives an RRC connectionreconfiguration message including synchronization settings from the basestation. An example of the above message is a handover command message.Also, the message may include reconfiguring a specific QoS flow of aspecific PDU session from a previous DRB to a new DRB. In operation 3i-45, the terminal receiving the RRC message performs DRBreconfiguration indicated in the RRC message. For example, it mayinclude content that QoS flow 1 is reconfigured from DRB 2 to DRB 3. Inaddition, the RRC layer of the terminal indicates that the above QoSflow and DRB reconfiguration are provided to the SDAP entity, and then,when the QoS flow 1 is received by the SDAP entity as DRB 2, thecorresponding packet is transmitted to the upper layer. If the SDAPreceives QoS flow 1 as DRB 3, the packet is delivered to the upper layerand a filtering operation is performed. That is, from that time on,packets of QoS flow 1 received from DRB 2 are discarded. This is toachieve in-sequence delivery.

FIG. 3J is a view illustrating overall terminal operation according toan embodiment of the disclosure.

After camping on a serving cell, the terminal establishes an RRCconnection with the cell and transitions to the connected mode (3 j-05).In operation 3 j-10, the terminal receives the configurations for DRBsthrough the RRC message of a base station. The configurations includedetailed layer (MAC, RLC, PDCP) configuration information of DRBs,information on DRBs to which each QoS flow is to be delivered, andinformation about which DRB is the default DRB. As an example of theconfiguration, DRB 1, DRB 2, and DRB 3 are configured in FIG. 3J, DRB 1is indicated as a default DRB, and QoS flow mapping corresponding to DRB1 and DRB 2 may be configured. In operation 3 j-15, the terminalreceives a downlink data packet transmitted by the base station. In theabove operation, the terminal receives the SDAP SDU through thepreconfigured DRB x and decodes the SDAP header of the correspondingpacket to check the QoS flow ID.

In operation 3 j-20, the terminal determines whether the SDAP packetreceived through DRB x is a new QoS flow packet, and performs differentoperations. If the packet received from the SDAP layer is a new QoS flowpacket (i.e., if the first packet of the new QoS flow is received in DRBx), the terminal performs the first operation. The first operation ofoperation 3 j-25 is an operation that allows the first packet of the newQoS flow to be processed and delivered first. When the terminal receivesthe SDAP SDU of the new QoS flow, the corresponding SDAP PDU isdelivered to the PDCP of the default DRB (or modified DRB) as anexpedited (ED) indicator to quickly process the QoS flow indicated bythe first packet (SDAP PDU). Here, the expedited (ED) indicator may beincluded as 1 bit in the PDCP header. Subsequently, in the PDCP layer, aPDCP sequence number (SN) is allocated to the corresponding PDCP SDU,and if the ED indicator is included, the PDCP PDU is transmitted to thelower layer with high priority. In addition, in the RLC layer, the RLCSN is allocated to the corresponding RLC SDU, and if the ED indicator isincluded, the corresponding RLC PDU is delivered to the lower layer withhigh priority. If the SDAP SDU received by the terminal is receivedthrough the preset DRB x, in operation 3 j-30, the terminal delivers thePDCP of the DRB x to the lower layer without any special action. Thatis, a separate expedited delivery operation is not configured.

In operation 3 j-35, the terminal receives an RRC connectionreconfiguration message including synchronization configurationinformation from the base station. An example of the above message is ahandover command message. Also, the message may include reconfiguring aspecific QoS flow of a specific PDU session from a previous DRB to a newDRB. In operation 3 j-40, the terminal receiving the RRC messageperforms DRB reconfiguration indicated by the RRC message. For example,content that QoS flow 1 is reconfigured from DRB 2 to DRB 3 may beincluded. In addition, the RRC layer of the terminal indicates that theabove QoS flow and DRB reconfiguration are indicated to the SDAP entity,and the operation is different depending on whether a new QoS flowpacket is received with the changed DRB. If SDAP receives QoS flow 1 asDRB 3, that is, if a new QoS flow packet is received as a modified DRB,the terminal delivers the packet to the upper layer in operation 3 j-50and performs a filtering operation. That is, from that time on, thepacket of QoS flow 1 received from DRB 2, that is, the previous DRB, isdiscarded. This is to achieve in-sequence delivery. On the other hand,if a new QoS flow packet is received by the previous DRB before beingreceived by the changed DRB, that is, when QoS flow 1 is received by theSDAP entity as DRB 2, the packet is transmitted to the upper layer.

FIG. 3K is a view illustrating the configuration of a terminal accordingto an embodiment of the disclosure.

Referring to FIG. 3K, the terminal includes a radio-frequency (RF)processor 3 k-10, a baseband processor 3 k-20, a storage unit 3 k-30,and a controller 3 k-40. The controller 3 k-40 may include amultiple-connection processor 3 k-42.

The RF processor 3 k-10 performs a function for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 3 k-10up-converts a baseband signal provided from the baseband processor 3k-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 3 k-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital-to-analog converter (DAC), ananalog-to-digital converter (ADC), etc. In FIG. 3K, although only oneantenna is illustrated, the terminal may have multiple antennas. Also,the RF processor 3 k-10 may include a plurality of RF chains.Furthermore, the RF processor 3 k-10 may perform beamforming. For thebeamforming, the RF processor 3 k-10 may adjust the phase and magnitudeof each of signals transmitted and received through multiple antennas orantenna elements. In addition, the RF processor may perform MIMO, andmay receive multiple layers when performing MIMO operations.

The baseband processor 3 k-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical-layerstandard of a system. For example, during data transmission, thebaseband processor 3 k-20 generates complex symbols by encoding andmodulating a transmission bit stream. In addition, upon receiving data,the baseband processor 3 k-20 restores the received bit stream throughdemodulation and decoding of the baseband signal provided from the RFprocessor 3 k-10. For example, in the case of conforming to anorthogonal frequency-division multiplexing (OFDM) method, whentransmitting data, the baseband processor 3 k-20 encodes and modulates atransmission bit stream to generate complex symbols, maps the complexsymbols to subcarriers, and then configures OFDM symbols via an inversefast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. In addition, when receiving data, the baseband processor 3k-20 divides the baseband signal provided from the RF processor 3 k-10into units of OFDM symbols, restores signals mapped to subcarriers viathe fast Fourier transform (FFT) operation, and then restores a receivedbit stream via demodulation and decoding.

The baseband processor 3 k-20 and the RF processor 3 k-10 transmit andreceive signals as described above. Accordingly, each of the basebandprocessor 3 k-20 and the RF processor 3 k-10 may be referred to as atransmitter, a receiver, a transceiver, or a communicator. Furthermore,at least one of the baseband processor 3 k-20 and the RF processor 3k-10 may include a plurality of communication modules to support aplurality of different radio access technologies. In addition, at leastone of the baseband processor 3 k-20 and the RF processor 3 k-10 mayinclude different communication modules to process signals in differentfrequency bands. For example, the different radio access technologiesmay include a wireless LAN (e.g., IEEE 802.11), a cellular network(e.g., LTE), and the like. In addition, the different frequency bandsmay include a super-high-frequency (SHF) (e.g., 2.NRHz, NRHz) band and amillimeter-wave (e.g., 60 GHz) band.

The storage unit 3 k-30 stores data such as a basic program, anapplication, and configuration information for the operation of theterminal. In particular, the storage unit 3 k-30 may store informationrelated to the second access node, which performs wireless communicationusing the second wireless access technology. The storage unit 3 k-30provides stored data in response to a request from the controller 3k-40.

The controller 3 k-40 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 3 k-40 transmits and receives signals through the basebandprocessor 3 k-20 and the RF processor 3 k-10. In addition, thecontroller 3 k-40 records and reads data in the storage unit 3 k-30. Tothis end, the controller 3 k-40 may include at least one processor. Forexample, the controller 3 k-40 may include a communication processor(CP) that performs control for communication and an applicationprocessor (AP) that controls an upper layer such as an application.

FIG. 3L is a view illustrating the configuration of a base stationaccording to an embodiment of the disclosure.

As illustrated in FIG. 3L, the base station includes an RF processor 3l-10, a baseband processor 3 l-20, a backhaul communicator 3 l-30, astorage unit 3 l-40, and a controller 3 l-50. The controller 3 l-50 mayinclude a multiple-connection processor 3 l-52.

The RF processor 3 l-10 performs a function for transmitting andreceiving a signal via a wireless channel, such as band conversion andamplification of the signal. That is, the RF processor 3 l-10up-converts a baseband signal provided from the baseband processor 3l-20 to an RF band signal and then transmits the same through anantenna, and down-converts an RF band signal received through theantenna to a baseband signal. For example, the RF processor 3 l-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, an ADC, etc. In FIG. 3L, although only oneantenna is illustrated, the first connection node may have multipleantennas. Also, the RF processor 3 l-10 may include a plurality of RFchains. Furthermore, the RF processor 3 l-10 may perform beamforming.For the beamforming, the RF processor 3 l-10 may adjust the phase andmagnitude of each of signals transmitted and received through multipleantennas or antenna elements. The RF processor may perform down-MIMOoperations by transmitting one or more layers.

The baseband processor 3 l-20 performs a function of conversion betweena baseband signal and a bit stream according to the physical-layerstandard of a first radio access technology. For example, during datatransmission, the baseband processor 3 l-20 generates complex symbols byencoding and modulating a transmission bit stream. In addition, uponreceiving data, the baseband processor 3 l-20 restores the received bitstream through demodulation and decoding of the baseband signal providedfrom the RF processor 3 l-10. For example, in the case of conforming tothe OFDM method, when transmitting data, the baseband processor 3 l-20encodes and modulates a transmission bit stream to generate complexsymbols, maps the complex symbols to subcarriers, and then configuresOFDM symbols via IFFT operation and CP insertion. In addition, whenreceiving data, the baseband processor 3 l-20 divides the basebandsignal provided from the RF processor 3 l-10 into units of OFDM symbols,restores signals mapped to subcarriers via the FFT operation, and thenrestores a received bit stream via demodulation and decoding. Thebaseband processor 3 l-20 and the RF processor 3 l-10 transmit andreceive signals as described above. Accordingly, each of the basebandprocessor 3 l-20 and the RF processor 3 l-10 may be referred to as atransmitter, a receiver, a transceiver, or a wireless communicator.

The backhaul communicator 3 l-30 provides an interface for performingcommunication with other nodes in a network. That is, the backhaulcommunicator 3 l-30 converts a bit stream transmitted from the basestation to another node, for example, an auxiliary base station or acore network, into a physical signal, and converts the physical signalreceived from the other node into a bit stream.

The storage unit 3 l-40 stores data such as a basic program, anapplication, and configuration information for the operation of theterminal. In particular, the storage unit 3 l-40 may store informationon bearers allocated to the connected terminal, measurement resultsreported from the connected terminal, and the like. In addition, thestorage unit 3 l-40 may store information serving as a criterion fordetermining whether to provide or interrupt multiple connections to theterminal. Then, the storage unit 3 l-40 provides stored data in responseto a request from the controller 3 l-50.

The controller 3 l-50 controls the overall operation of the terminalaccording to an embodiment of the disclosure. For example, thecontroller 3 l-50 transmits and receives signals through the basebandprocessor 3 l-20 and the RF processor 3 l-10 or through the backhaulcommunicator 3 l-30. In addition, the controller 3 l-50 records andreads data in the storage unit 3 l-40. To this end, the controller 3l-50 may include at least one processor.

The third embodiment of the disclosure is summarized as follows.

1. Main Points

-   -   Prioritizing the first packet of new QoS flow        -   The SDAP indicates to the PDCP whether expedited delivery            shall apply to the SDAP PDU.        -   The PDCP submits the corresponding PDCP PDU to the lower            layer ahead of PDCP PDUs waiting in the buffer. An            expedited-delivery indication can be added to the PDCP            header so that the receiver does not trigger the reordering            timer but performs delivery to the upper layer immediately.        -   The RLC submits the corresponding RLC PDU to the lower layer            ahead of RLC PDUs awaiting in the buffer.    -   In-sequence delivery during QoS flow remapping is preserved.        -   Assuming that QoS flow x is remapped from PDCP A to PDCP B            (or from DRB A to DRB B), in-sequence delivery is broken if            QoS flow x packet from PDCP A is delivered to the upper            layer after a packet from PDCP B is delivered.        -   Therefore, the simplest solution is simply to discard such            packets. The sequence is as follows.        -   1: An RRC message is received to relocate a QoS flow from            DRB_old to DRB_new in a PDU session.        -   2: The RRC indicates QoS relocation to the SDAP entity.        -   3: The SDAP entity starts filtering for the QoS flow once            the first packet of the QoS flow is received from the new            DRB (thereafter, SDAP PDUs of the QoS flow are discarded            from the old DRB).

2. Operations

-   -   UE: Camp on NR cell.    -   UE<->GNB: RRC connection establishment.    -   UE<-GNB: RRC connection reconfiguration.        -   DRB1, DRB 2 and DRB 3 are established.        -   DRB 1 is default DRB.        -   QoS flows mapped to DRB 1 and QoS flows mapped to DRB 2 are            indicated.    -   UE: SDAP SDU for QoS flow mapped to DRB 2 is received.        -   The SDAP submits the SDAP PDU to the PDCP of the DRB2 w/o ED            indication.    -   UE: An SDAP SDU for a new QoS flow is received by the SDAP.        -   The SDAP submits the SDAP PDU to the PDCP of default DRB            with ED indication.        -   The PDCP allocates the PDCP SN for the PDCP SDU. If ED is            indicated, the PDCP PDU is submitted to the lower layer with            ED indication ahead of PDCP PDUs having a lower COUNT.        -   RLC allocates RLC SN for the RLC SDU. If ED is indicated,            the RLC SDU is submitted to the lower layer ahead of RLC            PDUs with lower RLC SNs.    -   UE<-GNB: RRC connection reconfiguration with synchronous        reconfiguration indication (i.e., HO command).        -   QoS relocation is indicated for QoS flow 1 from DRB 2 to DRB            3.        -   The RRC indicates to the SDAP entity that QoS flow 1 is            relocated from DRB 2 to DRB 3.        -   The SDAP receives QoS flow 1 packet from DRB 2, then            delivers the packet to the upper layer.        -   The SDAP receives QoS flow 1 packet from DRB 3, then            delivers the packet to the upper layer and starts filtering            (or discarding) QoS flow 1 packets from DRB 2.

The particular embodiments of the disclosure described and shown in thespecification and the drawings have been presented to easily explain thetechnical contents of the embodiments of the disclosure and helpunderstanding of the embodiments of the disclosure, and are not intendedto limit the scope of the embodiments of the disclosure. Therefore, thescope of the disclosure should be construed to include, in addition tothe embodiments disclosed herein, all changes and modifications derivedon the basis of the technical idea of the disclosure.

The invention claimed is:
 1. A method of operating a terminal, themethod comprising: receiving, from a base station, a radio resourcecontrol (RRC) message comprising information indicating whether to useuplink data compression (UDC); receiving data from an upper applicationlayer of the terminal; compressing the data and encrypting thecompressed data; generating an uplink data compression (UDC) header anda service data adaptation protocol (SDAP) header together; generating ablock to which the UDC header and the SDAP header are bonded in theencrypted data; and transmitting the block to a lower layer of theterminal.
 2. The method of claim 1, wherein an encryption is notperformed on the UDC header, and a compression is not performed on theSDAP header.
 3. The method of claim 1, wherein the SDAP layer and thepacket data convergence protocol (PDCP) layer of the terminal areconfigured as one first-layer device, and wherein a compression and anencryption of the data and bonding of the UDC header and the SDAP headerare performed in the first-layer device.
 4. The method of claim 1,wherein the RRC message further comprises information indicating atleast one of a PDCP device, a bearer, an IP flow, or a quality ofservice (QoS) flow, to which the uplink data compression is applied. 5.A terminal comprising: a transceiver; and a controller configured to:receive a radio resource control (RRC) message comprising informationindicating whether to use uplink data compression (UDC) from a basestation, receive data from an upper application layer of the terminal,compress the data and encrypt the compressed data, generate an uplinkdata compression (UDC) header and a service data adaptation protocol(SDAP) header together, generate a block to which the UDC header and theSDAP header are bonded in the encrypted data, and transmit the block toa lower layer of the terminal.
 6. The terminal of claim 5, wherein anencryption is not performed on the UDC header, and a compression is notperformed on the SDAP header.
 7. The terminal of claim 5, wherein theSDAP layer and the packet data convergence protocol (PDCP) layer of theterminal are configured as one first-layer device, and wherein acompression and an encryption of the data and bonding of the UDC headerand the SDAP header are performed in the first-layer device.
 8. Theterminal of claim 5, wherein the RRC message further comprisesinformation indicating at least one of a PDCP device, a bearer, an IPflow, or a quality of service (QoS) flow, to which the uplink datacompression is applied.
 9. A method of operating a base station, themethod comprising: transmitting a radio resource control (RRC) messagecomprising information indicating whether to use uplink data compression(UDC) to a terminal; receiving first data from the terminal; obtainingan uplink data compression (UDC) header and a service data adaptationprotocol (SDAP) header, which are bonded in the first data; decoding anddecompressing second data from which the UDC header and the SDAP headerare removed; and transmitting the decompressed second data to an upperlayer of the base station.
 10. The method of claim 9, wherein anencryption is not performed on the UDC header of the first data, and acompression is not performed on the SDAP header.
 11. The method of claim9, wherein the SDAP layer and the packet data convergence protocol(PDCP) layer of the base station are configured as one first-layerdevice, and wherein a decompression, a decryption of the second data anda removal of the UDC header and SDAP header are performed in thefirst-layer device.
 12. The method of claim 9, wherein the RRC messagefurther comprises information indicating at least one of a PDCP device,a bearer, an IP flow, or a quality of service (QoS) flow, to which theuplink data compression is applied.
 13. A base station comprising: atransceiver; and a controller configured to: transmit a radio resourcecontrol (RRC) message comprising information indicating whether to useuplink data compression (UDC) to a terminal, receive first data from theterminal, obtain an uplink data compression (UDC) header and a servicedata adaptation protocol (SDAP) header, which are bonded in the firstdata, decode and decompress second data from which the UDC header andthe SDAP header are removed, and transmit the decompressed second datato an upper layer of the base station.
 14. The base station of claim 13,wherein an encryption is not performed on the UDC header of the firstdata, and a compression is not performed on the SDAP header.
 15. Thebase station of claim 13, wherein the SDAP layer and the packet dataconvergence protocol (PDCP) layer of the base station are configured asone first-layer device, wherein a decompression, a decryption of thesecond data and a removal of the UDC header and SDAP header areperformed in the first-layer device, and wherein the RRC message furthercomprises information indicating at least one of a PDCP device to whichthe uplink data compression is applied, a bearer, an IP flow, or aquality of service (QoS) flow.